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1.
Griffin, M. Pamela. Role for anions in pulmonaryendothelial permeability. J. Appl.Physiol. 83(2): 615-622, 1997.-Adrenergic stimulation reduces albumin permeation across pulmonary artery endothelial monolayers and induces changes in cell morphology that aremediated by Cl flux. Wetested the hypothesis that anion-mediated changes in endothelial cellsresult in changes in endothelial permeability. We measured permeationof radiolabeled albumin across bovine pulmonary arterial endothelialmonolayers when the extracellular anion was Cl,Br,I,F, acetate(Ac), gluconate(G), and propionate(Pr). Permeability toalbumin (Palbumin)was calculated before and after addition of 0.2 mM of thephosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX), whichreduces permeability. InCl, thePalbumin was 3.05 ± 0.86 × 106 cm/s andfell by 70% with the addition of IBMX. The initialPalbumin was lowest forPr andAc. InitialPalbumin was higher inBr,I,G, andF than inCl. A permeability ratiowas calculated to examine the IBMX effect. The greatest IBMX effect wasseen when Cl was theextracellular anion, and the order among halide anions wasCl > Br > I > F. Although the level ofextracellular Ca2+ concentration([Ca2+]o)varied over a wide range in the anion solutions,[Ca2+]odid not systematically affect endothelial permeability in this system.When Cl was theextracellular anion, varying[Ca2+]ofrom 0.2 to 2.8 mM caused a change in initialPalbumin but no changein the IBMX effect. The anion channel blockers4-acetamido-4-isothiocyanotostilbene-2,2-disulfonic acid(0.25 mM) and anthracene-9-carboxylic acid (0.5 mM) significantly altered initialPalbumin and the IBMXeffect. The anion transport blockers bumetanide (0.2 mM) and furosemide(1 mM) had no such effects. We conclude that extracellular anionsinfluence bovine pulmonary arterial endothelial permeability and thatthe pharmacological profile fits better with the activity of anionchannels than with other anion transport processes. 相似文献
2.
Hardarson Thorir; Skarphedinsson Jon O.; Sveinsson Torarinn 《Journal of applied physiology》1998,84(2):411-416
Hardarson, Thorir, Jon O. Skarphedinsson, and TorarinnSveinsson. Importance of the lactate anion in control ofbreathing. J. Appl. Physiol. 84(2):411-416, 1998.The purpose of this study was to examine theeffects of raising the arterialLa andK+ levels on minute ventilation(E) in rats. EitherLa or KCl solutions wereinfused in anesthetized spontaneously breathing Wistar rats to raisethe respective ion arterial concentration ([La] and[K+]) gradually tolevels similar to those observed during strenuous exercise.E, blood pressure, and heart rate wererecorded continuously, and arterial[La],[K+], pH, and bloodgases were repeatedly measured from blood samples. To prevent changesin pH during the Lainfusions, a solution of sodium lactate and lactic acid was used. Raising [La] to13.2 ± 0.6 (SE) mM induced a 47.0 ± 4.0% increase inE without any concomitant changes ineither pH or PCO2. Raising[K+] to 7.8 ± 0.11 mM resulted in a 20.3 ± 5.28% increase inE without changes in pH. Thus ourresults show that Laitself, apart from lactic acidosis, may be important in increasing E during strenuous exercise, and weconfirm earlier results regarding the role of arterial[K+] in the control ofE during exercise. 相似文献
3.
Age-related declines in maximal aerobic capacity in regularly exercising vs. sedentary women: a meta-analysis 总被引:3,自引:0,他引:3
Fitzgerald Margaret D.; Tanaka Hirofumi; Tran Zung V.; Seals Douglas R. 《Journal of applied physiology》1997,83(1):160-165
Fitzgerald, Margaret D., Hirofumi Tanaka, Zung V. Tran, andDouglas R. Seals. Age-related declines in maximal aerobic capacityin regularly exercising vs. sedentary women: a meta-analysis. J. Appl. Physiol. 83(1): 160-165, 1997.Our purpose was to determine the relationship between habitualaerobic exercise status and the rate of decline in maximal aerobiccapacity across the adult age range in women. A meta-analytic approachwas used in which mean maximal oxygen consumption(O2 max) values fromfemale subject groups (ages 18-89 yr) were obtained from thepublished literature. A total of 239 subject groups from 109 studiesinvolving 4,884 subjects met the inclusion criteria and werearbitrarily separated into sedentary (groups = 107; subjects = 2,256),active (groups = 69; subjects = 1,717), and endurance-trained (groups = 63; subjects = 911) populations.O2 max averaged 29.7 ± 7.8, 38.7 ± 9.2, and 52.0 ± 10.5 ml · kg1 · min1,respectively, and was inversely related to age within each population (r = 0.82 to 0.87, allP < 0.0001). The rate of decline inO2 max withincreasing subject group age was lowest in sedentary women (3.5ml · kg1 · min1· decade1), greater inactive women (4.4ml · kg1 · min1· decade1), andgreatest in endurance-trained women (6.2ml · kg1 · min1 · decade1)(all P < 0.001 vs. each other). Whenexpressed as percent decrease from mean levels at age ~25 yr, therates of decline inO2 max were similarin the three populations (10.0 to 10.9%/decade). Therewas no obvious relationship between aerobic exercise status and therate of decline in maximal heart rate with age. The results of thiscross-sectional study support the hypothesis that, in contrast to theprevailing view, the rate of decline in maximal aerobic capacity withage is greater, not smaller, in endurance-trained vs. sedentary women.The greater rate of decline inO2 max in endurance-trained populations may be related to their higher values asyoung adults (baseline effect) and/or to greater age-related reductions in exercise volume; however, it does not appear to berelated to a greater rate of decline in maximal heart rate with age. 相似文献
4.
Combined heart rate and activity improve estimates of oxygen consumption and carbon dioxide production rates 总被引:1,自引:0,他引:1
Moon, Jon K., and Nancy F. Butte. Combined heart rateand activity improve estimates of oxygen consumption and carbon dioxideproduction rates. J. Appl. Physiol.81(4): 1754-1761, 1996.Oxygen consumption(O2) andcarbon dioxide production (CO2) rates were measuredby electronically recording heart rate (HR) and physical activity (PA).Mean daily O2 andCO2 measurements by HR andPA were validated in adults (n = 10 women and 10 men) with room calorimeters. Thirteen linear and nonlinear functions of HR alone and HR combined with PA were tested as models of24-h O2 andCO2. Mean sleepO2 andCO2 were similar to basalmetabolic rates and were accurately estimated from HR alone[respective mean errors were 0.2 ± 0.8 (SD) and0.4 ± 0.6%]. The range of prediction errorsfor 24-h O2 andCO2 was smallestfor a model that used PA to assign HR for each minute to separateactive and inactive curves(O2, 3.3 ± 3.5%; CO2, 4.6 ± 3%). There were no significant correlations betweenO2 orCO2 errors and subject age,weight, fat mass, ratio of daily to basal energy expenditure rate, orfitness. O2,CO2, and energy expenditurerecorded for 3 free-living days were 5.6 ± 0.9 ml · min1 · kg1,4.7 ± 0.8 ml · min1 · kg1,and 7.8 ± 1.6 kJ/min, respectively. Combined HR and PA measured 24-h O2 andCO2 with a precisionsimilar to alternative methods. 相似文献
5.
Greater rate of decline in maximal aerobic capacity with age in physically active vs. sedentary healthy women 总被引:8,自引:0,他引:8
Tanaka Hirofumi; Desouza Christopher A.; Jones Pamela P.; Stevenson Edith T.; Davy Kevin P.; Seals Douglas R. 《Journal of applied physiology》1997,83(6):1947-1953
Tanaka, Hirofumi, Christopher A. DeSouza, Pamela P. Jones,Edith T. Stevenson, Kevin P. Davy, and Douglas R. Seals. Greater rate of decline in maximal aerobic capacity with age in physically active vs. sedentary healthy women. J. Appl.Physiol. 83(6): 1947-1953, 1997.Using ameta-analytic approach, we recently reported that the rate of declinein maximal oxygen uptake(O2 max) with age inhealthy women is greatest in the most physically active and smallest inthe least active when expressed in milliliters per kilogram per minuteper decade. We tested this hypothesis prospectively underwell-controlled laboratory conditions by studying 156 healthy, nonobesewomen (age 20-75 yr): 84 endurance-trained runners (ET) and 72 sedentary subjects (S). ET were matched across the age range forage-adjusted 10-km running performance. Body mass was positivelyrelated with age in S but not in ET. Fat-free mass was not differentwith age in ET or S. Maximal respiratory exchange ratio and rating ofperceived exertion were similar across age in ET and S, suggestingequivalent voluntary maximal efforts. There was a significant butmodest decline in running mileage, frequency, and speed with advancingage in ET.O2 max(ml · kg1 · min1)was inversely related to age (P < 0.001) in ET (r = 0.82) and S(r = 0.71) and was higher atany age in ET. Consistent with our meta-analysic findings,the absolute rate of decline inO2 max was greater inET (5.7ml · kg1 · min1 · decade1)compared with S (3.2 ml · kg1 · min1 · decade1;P < 0.01), but the relative (%)rate of decline was similar (9.7 vs 9.1%/decade; notsignificant). The greater absolute rate of decline inO2 max in ET comparedwith S was not associated with a greater rate of decline in maximalheart rate (5.6 vs. 6.2beats · min1 · decade1),nor was it related to training factors. The present cross-sectional findings provide additional evidence that the absolute, but not therelative, rate of decline in maximal aerobic capacity with age may begreater in highly physically active women compared with theirsedentary healthy peers. This difference does not appear to be relatedto age-associated changes in maximal heart rate, bodycomposition, or training factors. 相似文献
6.
Changes in maximum oxygen uptake during prolonged training, overtraining, and detraining in horses 总被引:2,自引:0,他引:2
Tyler Catherine M.; Golland Lorraine C.; Evans David L.; Hodgson David R.; Rose Reuben J. 《Journal of applied physiology》1996,81(5):2244-2249
Tyler, Catherine M., Lorraine C. Golland, David L. Evans,David R. Hodgson, and Reuben J. Rose. Changes in maximum oxygenuptake during prolonged training, overtraining, and detraining inhorses. J. Appl. Physiol. 81(5):2244-2249, 1996.Thirteen standardbred horses were trained asfollows: phase 1 (endurance training, 7 wk),phase 2 (high-intensity training, 9 wk),phase 3 (overload training, 18 wk), andphase 4 (detraining, 12 wk). Inphase 3, the horses were divided intotwo groups: overload training (OLT) and control (C). The OLT groupexercised at greater intensities, frequencies, and durations than groupC. Overtraining occurred after 31 wk of training and was defined as asignificant decrease in treadmill run time in response to astandardized exercise test. In the OLT group, there was a significantdecrease in body weight (P < 0.05).From pretraining values of 117 ± 2 (SE)ml · kg1 · min1,maximal O2 uptake(O2 max) increased by15% at the end of phase 1, and when signs of overtraining werefirst seen in the OLT group,O2 max was 29%higher (151 ± 2 ml · kg1 · min1in both C and OLT groups) than pretraining values. There was nosignificant reduction inO2 max until after 6 wk detraining whenO2 max was 137 ± 2 ml · kg1 · min1.By 12 wk detraining, meanO2 max was134 ± 2 ml · kg1 · min1,still 15% above pretraining values. When overtraining developed, O2 max was notdifferent between C and OLT groups, but maximal values forCO2 production (147 vs. 159 ml · kg1 · min1)and respiratory exchange ratio (1.04 vs. 1.11) were lower in the OLTgroup. Overtraining was not associated with a decrease inO2 max and, afterprolonged training, decreases inO2 max occurredslowly during detraining. 相似文献
7.
Training-induced alterations of carbohydrate metabolism in women: women respond differently from men 总被引:4,自引:0,他引:4
Friedlander Anne L.; Casazza Gretchen A.; Horning Michael A.; Huie Melvin J.; Piacentini Maria Francesca; Trimmer Jeffrey K.; Brooks George A. 《Journal of applied physiology》1998,85(3):1175-1186
We examined the hypothesis that glucose flux wasdirectly related to relative exercise intensity both beforeand after a 12-wk cycle ergometer training program [5days/wk, 1-h duration, 75% peakO2 consumption(O2 peak)] inhealthy female subjects (n = 17; age23.8 ± 2.0 yr). Two pretraining trials (45 and 65% of O2 peak)and two posttraining trials [same absolute workload (65% of oldO2 peak)and same relative workload (65% of new O2 peak)] wereperformed on nine subjects by using a primed-continuous infusion of[1-13C]- and[6,6-2H]glucose.Eight additional subjects were studied by using[6,6-2H]glucose.Subjects were studied postabsorption for 90 min of rest and 1 h ofcycling exercise. After training, subjects increased O2 peak by 25.2 ± 2.4%. Pretraining, the intensity effect on glucose kinetics wasevident between 45 and 65% ofO2 peak with rates ofappearance (Ra: 4.52 ± 0.25 vs. 5.53 ± 0.33 mg · kg1 · min1),disappearance (Rd: 4.46 ± 0.25 vs. 5.54 ± 0.33 mg · kg1 · min1),and oxidation (Rox: 2.45 ± 0.16 vs. 4.35 ± 0.26 mg · kg1 · min1)of glucose being significantly greater(P 0.05) in the 65% thanin the 45% trial. Training reducedRa (4.7 ± 0.30 mg · kg1 · min1),Rd (4.69 ± 0.20 mg · kg1 · min1),and Rox (3.54 ± 0.50 mg · kg1 · min1)at the same absolute workload (P 0.05). When subjects were tested at the same relative workload,Ra,Rd, andRox were not significantlydifferent after training. However, at both workloads after training,there was a significant decrease in total carbohydrate oxidation asdetermined by the respiratory exchange ratio. These results show thefollowing in young women: 1)glucose use is directly related to exercise intensity;2) training decreasesglucose flux for a given power output;3) when expressed asrelative exercise intensity, training does not affect the magnitude ofblood glucose flux during exercise; but4) training does reduce totalcarbohydrate oxidation. 相似文献
8.
Effect of luteal phase elevation in core temperature on forearm blood flow during exercise 总被引:1,自引:0,他引:1
Kolka, Margaret A., and Lou A. Stephenson. Effect ofluteal phase elevation in core temperature on forearm blood flow duringexercise. J. Appl. Physiol. 82(4):1079-1083, 1997.Forearm blood flow (FBF) as an index of skinblood flow in the forearm was measured in five healthy women by venousocclusion plethysmography during leg exercise at 80% peak aerobicpower and ambient temperature of 35°C (relative humidity 22%;dew-point temperature 10°C). Resting esophagealtemperature (Tes) was 0.3 ± 0.1°C higher in the midluteal than in the early follicular phase ofthe menstrual cycle (P < 0.05).Resting FBF was not different between menstrual cycle phases. TheTes threshold for onset of skinvasodilation was higher (37.4 ± 0.2°C) in midluteal than inearly follicular phase (37.0 ± 0.1°C; P < 0.05). The slope of the FBF toTes relationship was not different between menstrual cycle phases (14.0 ± 4.2 ml · 100 ml1 · min1 · °C1for early follicular and 16.3 ± 3.2 ml · 100 ml1 · min1 · °C1for midluteal phase). Plateau FBF was higher during exercise inmidluteal (14.6 ± 2.2 ml · 100 ml1 · min1 · °C1)compared with early follicular phase (10.9 ± 2.4 ml · 100 ml1 · min1 · °C1;P < 0.05). The attenuation of theincrease in FBF to Tes occurred when Tes was 0.6°C higher andat higher FBF in midluteal than in early follicular experiments(P < 0.05). In summary, the FBF response is different during exercise in the two menstrual cycle phasesstudied. After the attenuation of the increase in FBF and whileTes was still increasing, thegreater FBF in the midluteal phase may have been due to the effects ofincreased endogenous reproductive endocrines on the cutaneousvasculature. 相似文献
9.
Training improves endothelium-dependent vasodilation in resistance vessels of patients with heart failure 总被引:3,自引:0,他引:3
Katz Stuart D.; Yuen Jeannette; Bijou Rachel; Lejemtel Thierry H. 《Journal of applied physiology》1997,82(5):1488-1492
Katz, Stuart D., Jeannette Yuen, Rachel Bijou, and ThierryH. LeJemtel. Training improves endothelium-dependent vasodilation in resistance vessels of patients with heart failure.J. Appl. Physiol. 82(5):1488-1492, 1997.The effects of physical training onendothelium-dependent vasodilation in skeletal muscle resistance vessels were investigated in patients with heart failure. Forearm bloodflows(ml · min1 · 100 ml1) in response tobrachial arterial administration of acetylcholine (5 × 105 and 5 × 104 M at 1 ml/min) andnitroglycerin (5 × 106 and 5 × 105 M at 1 ml/min) weredetermined by strain-gauge venous occlusion plethysmography before andafter 8 wk of daily handgrip exercise in 12 patients with chronic heartfailure. After 8 wk of daily handgrip exercise, the vasodilatoryresponses to acetylcholine significantly increased from pretrainingvalues, i.e., 16.6 ± 2.0 vs. 8.6 ± 1.3 ml · min1 · 100 ml1(P < 0.05) and 27.5 ± 1.5 vs. 14.6 ± 1.7 ml · min1 · 100 ml1(P < 0.05), respect- ively,whereas the vasodilatory responses to nitroglycerin did notchange. Handgrip exercise training appears to specificallyenhance endothelium-dependent vasodilation in the forearm skeletalmuscle circulation of patients with heart failure. 相似文献
10.
Diffusional permeability (P) to sucrose(Psuc) andNa+(PNa+)was determined in specimens of rabbit sternal parietal pericardium,which may be obtained without stripping. Specimens were mounted in anUssing apparatus with 3H-labeledsucrose and22Na+in a luminal (L) or interstitial (I) chamber.Psuc was 2.16 ± 0.44 for LI and 2.63 ± 0.45 (SE) × 105 cm/s for IL,i.e., ~10 times smaller than that previously obtained in strippedspecimens of pleura despite the similarity of intercellular junctionsin pericardium and pleural mesothelium of various species. Thesefindings suggest that previousPsuc wasoverestimated because stripping damages the mesothelium.PNa+ (×105 cm/s) was 7.07 ± 0.71 for LI and 7.37 ± 0.69 × 105 cm/s for IL.Measurements were also done with phospholipids, which are adsorbed onthe luminal side of mesothelium in vivo. With phospholipids in L,Psuc was 0.75 ± 0.10 and 0.65 ± 0.08 andPNa+was 3.80 ± 0.32 and 3.76 ± 0.15 × 105 cm/s for LI andIL, respectively, i.e., smaller than without phospholipids.With phospholipids in I (where they are not adsorbed), Psuc (2.33 ± 0.42 × 105 cm/s) andPNa+(7.01 ± 0.45 × 105 cm/s) were similar tothose values without phospholipids. Hence, adsorbed phospholipidsdecrease P of mesothelium. If themesothelium were scraped away from the specimen,Psuc of theconnective tissue would be 13.2 ± 0.76 × 105 cm/s.Psuc of themesothelium, computed fromPsuc of theunscraped and scraped specimens, corrected for the effect of unstirredlayers (2.54 and 19.4 × 105 cm/s, respectively),was 2.92 and 0.74 × 105 cm/s without and withphospholipids, respectively. Hence, most of the resistance to diffusionof the pericardium is provided by the mesothelium. 相似文献
11.
Padilla Jaime; Garcia-Villalon Angel Luis; Fernandez Nuria; Monge Luis; Gomez Bernardino; Dieguez Godofredo 《Journal of applied physiology》1998,85(6):2205-2212
To analyze the effect of hyperthermia on thevascular response, the isometric response of isolated rabbit femoralartery segments was recorded at 37°C and hyperthermia (41 and44°C). Contraction to potassium (5 × 103-5 × 102 M) was significantlygreater at 41 and 44 than at 37°C and increased by inhibition ofnitric oxide (NO) synthesis withN-nitro-L-arginine(L-NNA;104 M) or endotheliumremoval at 37°C but not at 41 or 44°C. Norepinephrine (109-104M) produced a concentration-dependent contraction greater at 41 or 44 than at 37°C and not modified by endothelium removal orL-NNA at either temperature.Phenylephrine(109-104M) produced a contraction increased by warming to 44°C but not to41°C. The specific2-adrenoceptor agonist BHT-920produced a weak contraction, reduced by the1-adrenoceptor antagonist prazosin (106 M) andincreased at 44°C but not at 41°C. The concentration-dependent contraction to endothelin-1 (ET-1;1011-107M) was increased by warming to 41 and 44°C and by endothelium removal or L-NNA at 37°C butnot at 41 or 44°C. Response to ET-1 was reduced by endothelinETA-receptor antagonist BQ-123(105 M) andETB-receptor antagonist BQ-788(105 M). In arteriesprecontracted with ET-1(108-3 × 108 M), relaxation tosodium nitroprusside(108-104M) was increased at 41 and 44°C vs. at 37°C, but that of ACh (108-104M) or adenosine(108-104M) was not different at all temperatures studied. Relaxation to ACh,but not adenosine, was reduced similarly byL-NNA at all temperaturesstudied. These results suggest hyperthermia in muscular arteries mayinhibit production of, and increase dilatation to, NO, resulting inunchanged relaxation to ACh and increased constriction to KCl and ET-1,and may increase constriction to stimulation of1-adrenoceptors byNO-independent mechanisms. 相似文献
12.
Effects of dopamine and domperidone on ventilatory sensitivity to hypoxia after 8h of isocapnic hypoxia 总被引:1,自引:0,他引:1
Pedersen Michala E.F.; Dorrington Keith L.; Robbins Peter A. 《Journal of applied physiology》1999,86(1):222-229
Acclimatization to altitude involves an increase in the acutehypoxic ventilatory response (AHVR). Because low-dose dopamine decreases AHVR and domperidone increases AHVR, the increase in AHVR ataltitude may be generated by a decrease in peripheral dopaminergicactivity. The AHVR of nine subjects was determined with and without aprior period of 8 h of isocapnic hypoxia under each of threepharmacological conditions: 1)control, with no drug administered;2) dopamine (3 µg · min1 · kg1);and 3) domperidone (Motilin, 40 mg).AHVR increased after hypoxia (P 0.001). Dopaminedecreased (P 0.01), and domperidone increased (P 0.005) AHVR. The effect of both drugs on AHVR appearedlarger after hypoxia, an observation supported by a significantinteraction between prior hypoxia and drug in the analysis of variance(P 0.05). Although the increasedeffect of domperidone after hypoxia of 0.40 l · min1 · %saturation1[95% confidence interval (CI) 0.11 to 0.92 l · min1 · %1]did not reach significance, the lower limit for this confidence interval suggests that little of the increase in AHVR after sustained hypoxia was brought about by a decrease in peripheral dopaminergic inhibition. 相似文献
13.
Wapnir, Raul A., Maria C. Sia, and Stanley E. Fisher.Enhancement of intestinal water absorption and sodium transport byglycerol in rats. J. Appl. Physiol.81(6): 2523-2527, 1996.Glycerol (Gly) is a hydrophilic,absorbable, and energy-rich solute that could make water absorptionmore efficient. We investigated the use of Gly in a high-energybeverage containing corn syrup (CS) by using a small intestineperfusion procedure in the rat, an approach shown earlier to providegood preclinical information. The effectiveness of several formulationswith Gly and CS was compared with commercial products and toexperimental formulas where Gly substituted for glucose (Glc). TheCS-Gly combination was more effective than preparations on the marketcontaining sucrose and Glc-fructose syrups (G-P and G-L, respectively)in maintaining a net water absorption balance in the test jejunal segment [CS-Gly = 0.021 ± 0.226, G-L = 1.516 ± 0.467, and G-P = 0.299 ± 0.106 (SE)µl · min1 · cm1(P = 0.0113)] and in reducingsodium release into the lumen [CS-Gly = 133.2 ± 16.2, G-L = 226.7 ± 25.2, and G-P = 245.6 ± 23.4 nmol · min1 · cm1(P = 0.0022)]. In otherpreparations, at equal CS concentrations (60 and 80 g/l, respectively),Gly clearly improved net water absorption over a comparableGlc-containing product [CS60-Gly = 0.422 ± 0.136 and CS80-Gly = 0.666 ± 0.378 vs. CS60-Glc = 0.282 ± 0.200 andCS80-Glc = 1.046 ± 0.480 µl · min1 · cm1(P = 0.0019)]. On the basis ofthe data of this rat intestine perfusion model, Gly could be a usefulingredient in energy-rich beverages and might enhance fluid absorptionin humans. 相似文献
14.
Skeletal muscle oxidative enzyme capacity is impaired inpatients suffering from emphysema and chronic obstructive pulmonary disease. This effect may result as a consequence of the physiological derangements because of the emphysema condition or, alternatively, as aconsequence of the reduced physical activity level in these patients.To explore this issue, citrate synthase (CS) activity was measured inselected hindlimb muscles and the diaphragm of Syrian Golden hamsters 6 mo after intratracheal instillation of either saline (Con,n = 7) or elastase [emphysema(Emp); 25 units/100 g body weight, n = 8]. Activity level was monitored, and no difference betweengroups was found. Excised lung volume increased with emphysema (Con,1.5 ± 0.3 g; Emp, 3.0 ± 0.3 g,P < 0.002). Emphysema significantly reduced CS activity in the gastrocnemius (Con, 45.1 ± 2.0; Emp, 39.2 ± 0.8 µmol · min1 · gwet wt1,P < 0.05) and vastus lateralis (Con,48.5 ± 1.5; Emp, 44.9 ± 0.8 µmol · min1 · gwet wt1,P < 0.05) but not in the plantaris(Con, 47.4 ± 3.9; Emp, 48.0 ± 2.1 µmol · min1 · gwet wt1,P < 0.05) muscle. In contrast, CSactivity increased in the costal (Con, 61.1 ± 1.8; Emp, 65.1 ± 1.5 µmol · min1 · gwet wt1,P < 0.05) and crural (Con, 58.5 ± 2.0; Emp, 65.7 ± 2.2 µmol · min1 · gwet wt1, P < 0.05) regions of the diaphragm. These data indicate that emphysema perse can induce decrements in the oxidative capacity of certainnonventilatory skeletal muscles that may contribute to exerciselimitations in the emphysematous patient. 相似文献
15.
The distributionof TmDOTP5 in rat tissuewas compared with CoEDTA,an anionic complex previously used as a marker of extracellular space.Heart, liver, muscle, blood, and urine were collected from rats afterinfusion of either complex and were quantitatively analyzed by atomicabsorption spectroscopy. Although totalTmDOTP5 in blood and tissuewas consistently lower (0.88 ± 0.04;n = 6) thanCoEDTA after an identicalinfusion protocol (presumably because of some association of thephosphonate complex with bone), a comparison of blood and tissuecontents indicated that the two anionic complexes distributed intoidentical extracellular spaces. Relative extracellular space in the invivo liver, as determined byTmDOTP5 andCoEDTA, was 0.18 ± 0.02 and 0.15 ± 0.01, respectively. The corresponding relativeextracellular space values for the in vivo heart reported by the twoagents were identical (0.11 ± 0.02). Experiments were alsoperformed to evaluate the washout kinetics ofTmDOTP5 from anesthesizedrats. In rats given a total dose of 0.16 mmol TmDOTP5, 81% appeared inurine by 180 min, <2% was found in all remaining soft tissue,leaving ~18% undetected. The rate of Tm appearance in urine was fitto a standard pharmacokinetic model that included four tissuecompartments: plasma, one fast equilbrating space, one slowequilibrating space, and one very slow equilibrating space (presumablybone). The best fit result suggests that the highly chargedTmDOTP5 complex is clearedfrom plasma more rapidly than is the typical lower charged Gd-basedcontrast agents and that release from bone is slow compared with renal clearance. 相似文献
16.
Ameredes Bill T.; Brechue William F.; Stainsby Wendell N. 《Journal of applied physiology》1998,84(6):1909-1916
Repetitiveisometric tetanic contractions (1/s) of the caninegastrocnemius-plantaris muscle were studied either at optimal length(Lo) or shortlength (Ls;~0.9 · Lo),to determine the effects of initial length on mechanical and metabolicperformance in situ. Respective averages of mechanical and metabolicvariables were(Lo vs.Ls, allP < 0.05) passive tension (preload) = 55 vs. 6 g/g, maximal active tetanic tension(Po) = 544 vs. 174 (0.38 · Po)g/g, maximal blood flow () = 2.0 vs. 1.4 ml · min1 · g1,and maximal oxygen uptake(O2) = 12 vs. 9 µmol · min1 · g1.Tension at Lodecreased to0.64 · Po over20 min of repetitive contractions, demonstrating fatigue; there were nosignificant changes in tension atLs. In separatemuscles contracting atLo, was set to that measured atLs (1.1 ml · min1 · g1),resulting in decreased O2(7 µmol · min1 · g1),and rapid fatigue, to0.44 · Po. Thesedata demonstrate that 1)muscles at Lohave higher andO2 values than those at Ls;2) fatigue occurs atLo with highO2, adjusting metabolic demand (tension output) to match supply; and3) the lack of fatigue atLs with lowertension, , andO2 suggestsadequate matching of metabolic demand, set low by shortmuscle length, with supply optimized by low preload. Thesedifferences in tension andO2 betweenLo andLs groupsindicate that muscles contracting isometrically at initial lengthsshorter than Loare working under submaximal conditions. 相似文献
17.
Smaller lungs in women affect exercise hyperpnea 总被引:2,自引:0,他引:2
McClaran Steven R.; Harms Craig A.; Pegelow David F.; Dempsey Jerome A. 《Journal of applied physiology》1998,84(6):1872-1881
We subjected 29 healthy young women (age: 27 ± 1 yr) with a wide range of fitness levels [maximal oxygenuptake (O2 max): 57 ± 6 ml · kg1 · min1;35-70ml · kg1 · min1]to a progressive treadmill running test. Our subjects had significantly smaller lung volumes and lower maximal expiratory flow rates, irrespective of fitness level, compared with predicted values for age-and height-matched men. The higher maximal workload in highly fit(O2 max > 57 ml · kg1 · min1,n = 14) vs. less-fit(O2 max < 56 ml · kg1 · min1,n = 15) women caused a higher maximalventilation (E) with increased tidal volume (VT)and breathing frequency (fb) atcomparable maximal VT/vitalcapacity (VC). More expiratory flow limitation (EFL; 22 ± 4% ofVT) was also observed duringheavy exercise in highly fit vs. less-fit women, causing higherend-expiratory and end-inspiratory lung volumes and greater usage oftheir maximum available ventilatory reserves.HeO2 (79% He-21%O2) vs. room air exercise trialswere compared (with screens added to equalize external apparatusresistance). HeO2 increasedmaximal expiratory flow rates (20-38%) throughout the range ofVC, which significantly reduced EFL during heavy exercise. When EFL wasreduced with HeO2, VT,fb, andE (+16 ± 2 l/min) weresignificantly increased during maximal exercise. However, in theabsence of EFL (during room air exercise),HeO2 had no effect onE. We conclude that smaller lungvolumes and maximal flow rates for women in general, and especiallyhighly fit women, caused increased prevalence of EFL during heavyexercise, a relative hyperinflation, an increased reliance onfb, and a greater encroachment onthe ventilatory "reserve." Consequently,VT andE are mechanically constrained duringmaximal exercise in many fit women because the demand for highexpiratory flow rates encroaches on the airways' maximum flow-volumeenvelope. 相似文献
18.
Effect of inhibition of nitric oxide synthesis on the diaphragmatic microvascular response to hypoxia 总被引:1,自引:0,他引:1
Ward, Michael E. Effect of inhibition of nitric oxidesynthesis on the diaphragmatic microvascular response to hypoxia. J. Appl. Physiol. 81(4):1633-1641, 1996.The purpose of this study was to determine theeffect of inhibition of nitric oxide (NO) release on the diaphragmaticmicrovascular responses to hypoxia. In -chloralose-anesthetizedmongrel dogs, the microcirculation of the vascularly isolated ex vivoleft hemidiaphragm was studied by intravital microscopy. The diaphragmwas pump perfused with blood diverted from the femoral artery through aseries of membrane oxygenators. The responses to supramaximalconcentrations of sodium nitroprusside, moderate hypoxia (phrenicvenous PO2 27 Torr), andsevere hypoxia (phrenic venous PO2 15 Torr) were recorded before and after an infusion ofNG-nitro-L-arginine(L-NNA; 6 × 104 M) into the phreniccirculation for 20 min. Under control conditions, diaphragmatic bloodflow was 12.4 ± 1.1 ml · min1 · 100 g1. Diaphragmatic bloodflows recorded during moderate and severe hypoxia were 15.6 ± 1.2 and 24.3 ± 1.5 ml · min1 · 100 g1, respectively(P < 0.05 for both compared withcontrol values). Treatment withL-NNA reduced diaphragmaticblood flow to 9.6 ± 0.8 ml · min1 · 100 g1 under control conditions(P < 0.05) and caused arteriolarvasoconstriction to a degree that was dependent on vessel size (i.e.,larger vessels constricted more than smaller vessels).L-NNA eliminated the increase inblood flow during moderate hypoxia and inhibited arteriolar dilation byan amount that was related to vessel size (i.e., dilation of largervessels was inhibited more than that of smaller vessels). Inhibition ofNO synthesis had no effect on the increase in diaphragmatic blood flow(23.6 ± 1.9 ml · min1 · 100 g1;P > 0.05 compared with that duringsevere hypoxia before treatment withL-NNA) or arteriolar diametersduring severe hypoxia. NO release plays a role in the diaphragmaticvascular response to hypoxia, but this role is limited to dilation oflarger arterioles during hypoxia of moderate severity. 相似文献
19.
Training-induced alterations of glucose flux in men 总被引:5,自引:0,他引:5
Friedlander Anne L.; Casazza Gretchen A.; Horning Michael A.; Huie Melvin J.; Brooks George A. 《Journal of applied physiology》1997,82(4):1360-1369
Friedlander, Anne L., Gretchen A. Casazza, Michael A. Horning, Melvin J. Huie, and George A. Brooks. Training-induced alterations of glucose flux in men. J. Appl.Physiol. 82(4): 1360-1369, 1997.We examined thehypothesis that glucose flux was directly related to relative exerciseintensity both before and after a 10-wk cycle ergometer trainingprogram in 19 healthy male subjects. Two pretraining trials [45and 65% of peak O2 consumption(O2 peak)] andtwo posttraining trials (same absolute and relative intensities as 65%pretraining) were performed for 90 min of rest and 1 h of cyclingexercise. After training, subjects increasedO2 peak by9.4 ± 1.4%. Pretraining, the intensity effect on glucose kinetics was evident with rates of appearance(Ra; 5.84 ± 0.23 vs. 4.73 ± 0.19 mg · kg1 · min1),disappearance (Rd; 5.78 ± 0.19 vs. 4.73 ± 0.19 mg · kg1 · min1),oxidation (Rox; 5.36 ± 0.15 vs. 3.41 ± 0.23 mg · kg1 · min1),and metabolic clearance (7.03 ± 0.56 vs. 5.20 ± 0.28 ml · kg1 · min1)of glucose being significantly greater(P 0.05) in the 65% than the 45%O2 peak trial. WhenRd was expressed as a percentage of total energy expended per minute(Rd E), there was nodifference between the 45 and 65% intensities. Training did reduceRa (4.63 ± 0.25),Rd (4.65 ± 0.24),Rox (3.77 ± 0.43), andRd E (15.30 ± 0.40 to12.85 ± 0.81) when subjects were tested at the same absolute workload (P 0.05). However, whenthey were tested at the same relative workload,Ra,Rd, andRd E were not different,although Rox was lowerposttraining (5.36 ± 0.15 vs. 4.41 ± 0.42, P 0.05). These results show1) glucose use is directly relatedto exercise intensity; 2) trainingdecreases glucose flux for a given power output;3) when expressed as relativeexercise intensity, training does not affect the magnitude of bloodglucose use during exercise; 4)training alters the pathways of glucose disposal. 相似文献
20.
Zhang Haibo; Rogiers Peter; Smail Nadia; Cabral Ana; Preiser Jean-Charles; Peny Marie-Odile; Vincent Jean-Louis 《Journal of applied physiology》1997,83(4):1164-1173
Zhang, Haibo, Peter Rogiers, Nadia Smail, Ana Cabral,Jean-Charles Preiser, Marie-Odile Peny, and Jean-Louis Vincent.Effects of nitric oxide on blood flow distribution andO2 extraction capabilities duringendotoxic shock. J. Appl. Physiol.83(4): 1164-1173, 1997.The effects of the nitric oxide (NO)synthase inhibitorNG-monomethyl-L-arginine(L-NMMA) and the NO donor3-morpholinosydnonimine (SIN-1) were tested in 18 endotoxic dogs. L-NMMA infusion(10 mg · kg1 · h1)increased arterial and pulmonary artery pressures and systemic andpulmonary vascular resistances but decreased cardiac index, leftventricular stroke work index, and blood flow to the hepatic, portal,mesenteric, and renal beds. SIN-1 infusion (2 µg · kg1 · min1)increased cardiac index; left ventricular stroke work index; andhepatic, portal, and mesenteric blood flow. It did not significantly influence arterial and pulmonary artery pressures but decreased renalblood flow. The critical O2delivery was similar in the L-NMMA group and in the controlgroup (13.3 ± 1.6 vs. 12.8 ± 3.3 ml · kg1 · min1)but lower in the SIN-1 group (9.1 ± 1.8 ml · kg1 · min1,both P < 0.05). The criticalO2 extraction ratio was alsohigher in the SIN-1 group than in the other groups (58.7 ± 10.6 vs.42.2 ± 7.6% in controls, P < 0.05; 43.0 ± 15.5% inL-NMMA group,P = not significant). We conclude thatNO is not implicated in the alterations inO2 extraction capabilitiesobserved early after endotoxin administration. 相似文献