Pyridoxalated hemoglobin polyoxyethylene conjugate reverses hyperdynamic circulation in septic sheep

We investigated the effects of modifiedhemoglobin on regional blood flow and function of different organsduring hyperdynamic sepsis. Fourteen sheep were surgically prepared forthe study. After a 5-day recovery period, a continuous infusion of livePseudomonas aeruginosa bacteria wasbegun and maintained for 48 h. At 24 h, after a hyperdynamiccirculation had developed, the animals were randomly assigned to twogroups: 1) a treatment group(n = 7) that received an infusion with100 mg/kg pyridoxalated hemoglobin polyoxyethylene conjugate (PHP) over30 min and 2) a control group (n = 7) that received only thevehicle. PHP infusion increased mean arterial pressure from 86 ± 2.8 to 101.8 ± 3.5 mmHg (P < 0.05) and systemic vascular resistance index from 769 ± 42.1 to 1,087 ± 56.8 dyn · s · m² · cm⁵(P < 0.05). PHPinfusion did not decrease regional blood flow, measured withfluorescent microspheres, below the baseline values in any of theanalyzed tissues. None of the investigated blood chemistry variablesshowed any changes indicative of impaired organ function after PHPinfusion. In our model of ovine sepsis we found no side effects afterPHP infusion that would limit the use of PHP as a nitric oxidescavenger in sepsis.

     

Perfluorochemical rescue after surfactant treatment: effect of perflubron dose and ventilatory frequency

Wolfson, Marla R., Nancy E. Kechner, Robert F. Roache,Jean-Pierre DeChadarevian, Helena E. Friss, S. David Rubenstein, andThomas H. Shaffer. Perfluorochemical rescue after surfactant treatment: effect of perflubron dose and ventilatory frequency. J. Appl. Physiol. 84(2): 624-640, 1998.To test the hypotheses that perfluorochemical (PFC) liquidrescue after natural surfactant (SF) treatment would improve pulmonaryfunction and histology and that this profile would be influenced by PFCdose or ventilator strategy, anesthetized preterm lambs(n = 31) with respiratory distresswere studied using nonpreoxygenated perflubron. All animals received SFat 1 h and were randomized at 2 h as follows and studied to 4 h postnatal age: 1) conventionalmechanical gas ventilation (n = 8),2) 30 ml/kg perflubron with gasventilation [partial liquid ventilation (PLV)] at 60 breaths/min (n = 8),3) 10 ml/kg perflubron with PLV at60 breaths/min (n = 7), and4) 10 ml/kg perflubron with PLV at30 breaths/min (n = 8). All animalstolerated instillation without additional cardiopulmonary instability.All perflubron-rescued groups demonstrated sustained improvement in gasexchange, respiratory compliance, and reduction in pressure requirements relative to animals receiving SF alone. Improvement wasdirectly related to perflubron dose and breathing frequency; peakinspiratory pressure required to achieve physiological gas exchange waslower in the higher-dose and -frequency groups, and mean airwaypressure was lower in the lower-frequency group. Lung expansion wasgreater and evidence of barotrauma was less in the higher-dose and-frequency group; regional differences in expansion were not differentas a function of dose but were greater in the lower-frequency group.Regional differences in lung perflubron content were reduced in thehigher-dose and -frequency groups and greatest in the lower-dose and-frequency group. The results suggest that, whereas PLV of theSF-treated lung improves gas exchange and lung mechanics, theprotective benefits of perflubron in the lung may depend on dose andventilator strategy to optimize PFC distribution and minimize exposureof the alveolar-capillary membrane to a gas-liquid interface.

     

Postnatal lung function and protein permeability after fetal or maternal corticosteroids in preterm lambs

Rebello, Celso M., Machiko Ikegami, M. Gore Ervin, Daniel H. Polk, and Alan H. Jobe. Postnatal lung function and protein permeability after fetal or maternal corticosteroids in preterm lambs.J. Appl. Physiol. 83(1): 213-218, 1997.We evaluated postnatal lung function andintravascular albumin loss to tissues of 123-days-gestation pretermsurfactant-treated and ventilated lambs 15 h after direct fetal(n = 8) or maternal(n = 9) betamethasone treatment orsaline placebo (n = 9). Thebetamethasone-treated groups had similar increases in dynamiccompliances, ventilatory efficiency indexes, and lung volumes relativeto controls (P < 0.05). The lossesof ¹²⁵I-labeled albumin fromblood, a marker of intravascular integrity, and the recoveries of¹²⁵I-albumin in muscle and brainwere similar for control and betamethasone-exposed lambs.Betamethasone-treated lambs had lower recoveries of¹²⁵I-albumin in lung tissues andin alveolar washes than did controls (P < 0.01). Although blood pressureswere higher for the treated groups (P < 0.05), all groups had similar blood volumes, cardiac outputs, andorgan blood flows. Maternal or fetal treatment with betamethasone 15 hbefore preterm delivery equivalently improved postnatal lung function,reduced albumin recoveries in lungs, and increased blood pressures.However, prenatal betamethasone had no effects on the systemicintravascular losses of albumin or did not change blood volumes.

     

Ventricular activation during sympathetic imbalance and its computational reconstruction

We characterized the epicardialactivation sequence during a norepinephrine (NE)-induced ventriculararrhythmia in anesthetized pigs and studied factors that modulatedit. Subepicardial NE infusion caused the QRS complex to invertwithin a single beat (n = 35 animals, 101 observations), and the earliest epicardial activation consistentlyshifted to the randomly located infusion site (n = 14).This preceded right atrial activation, whereas the total ventricularepicardial activation time increased from 20 ± 4 to 50 ± 9 ms (P < 0.01). These events were accompanied by aventricular tachycardia and a drop in left ventricular pressure, whichwere fully reversed after the infusion was stopped. Epicardial pacing at the infusion site mimicked all electrical and hemodynamic changes induced by NE. The arrhythmia was prevented by propranolol and abolished by cardiac sympathetic or vagal nerve stimulation. Focal automaticity was computationally reconstructed using a two-dimensional sheet of 256 × 256 resistively coupled ventricular cells, where calcium handling was abnormally high in the central region. We concludethat adrenergic stimulation to a small region of the ventricle elicitstriggered automaticity and that computational reconstruction implicatescalcium overload. Interventions that reduce spatial inhomogeneities ofintracellular calcium may prevent this type of arrhythmia.

     

Use of nonlinear methods to assess effects of clonidine on blood pressure in spontaneously hypertensive rats

In spontaneously hypertensive rats (SHR),chronic infusion of clonidine failed to decrease blood pressure andblood pressure variability. We used nonlinear methods to get a deeperinsight on the effects of clonidine on blood pressure dynamics. For 24 h and 4 wk, clonidine (0.1 mg · kg¹ · day¹sc) was infused by minipumps in the conscious SHRs, and, for comparison, a vehicle was infused in SHRs and in Wistar-Kyoto rats.Blood pressure was recorded for 30 min before and after treatments. Weused the Lyapunov exponent, approximated by the inverse of thel_max indexderived from the recurrence plot method, to characterize nonlineardynamics. Before treatment,l_max index ofblood pressure was lower (P < 0.01)in the SHRs than in the Wistar-Kyoto rats. Clonidine significantlyincreased l_max(P < 0.01) to the level observed innormotensive rats, at 24 h and up to 4 wk after infusion. We concludethat clonidine has a significant chronic effect on blood pressuredynamics, as evidenced by nonlinear methods. Our study also suggeststhat the mechanisms governing blood pressure variations are nonlinear.

     

Inhaled nitric oxide prevents left ventricular impairment during endotoxemia

We evaluated theeffect of long-term inhalation of nitric oxide (NO) on cardiaccontractility after endotoxemia by using the end-systolicelastance of the left ventricle (LV) as a load-independent contractility index. Chronic instrumentation in 12 pigs included implantation of two pairs of endocardial dimension transducers tomeasure LV volume and a micromanometer to measure LV pressure. One weeklater, the animals were divided into a control group (n = 6) or a NO group(n = 6). All animals receivedintravenous Escherichia coliendotoxin (10 µg · kg¹ · h¹)and equivalent lactated Ringer solution. NO inhalation (20 parts/million) was begun 30 min after the initiation of endotoxemia andwas continued for 24 h. In both groups, tachycardia, pulmonaryhypertension, and systemic hyperdynamic changes were noted. Theend-systolic elastance in the control group was significantly decreasedbeyond 7 h. NO inhalation maintained the end-systolic elastance atbaseline levels and prevented its impairment. These findings indicatethat NO exerts a protective effect on LV contractility in this model of endotoxemia.

     

Pharmacokinetics, immunogenicity, and efficacy of dimeric TNFR binding proteins in healthy and bacteremic baboon

Immunogenicity, pharmacokinetics, and therapeutic efficacy ofthree novel dimeric soluble tumor necrosis factor (TNF)-receptor Iconstructs [TNF-binding protein (bp)] were evaluated in 28 baboons, 12 of which were healthy and 16 were challenged with a lethal Escherichia coli bacteremia. The threeconstructs differed only in the number of extracellular domains of theTNF receptor I and were dimerized with polyethylene glycol. Althoughall three constructs had generally similar pharmacokinetics whenadministered to a naive animal, they differed quantitatively in theirimmunogenicity. Antibodies were detected more frequently, and titerswere significantly higher (P < 0.05)in both healthy and septic baboons that received the 4.0-domain TNF-bpconstruct, compared with animals receiving the 2.6-domain construct.When the TNF-bp constructs were administered a second time (21 dayslater), the half-lives of the three constructs were significantlyshorter in animals that had an antibody response after the firstinjection. In contrast, all three TNF-bp constructs were equallyeffective at improving outcome, blocking a systemic TNF- response,and attenuating the cytokine responses when administered at a dose of1.0 mg/kg body wt 1 h before a lethal E. coli infusion. The findings suggest that immunogenicityof TNF-bp constructs can be altered by changing the number offunctional domains, without affecting their capacity to neutralizeTNF- and to abrogate TNF-mediated pathology.

     

Escherichia coli as an expression system for K(+) transport systems from plants

The value of theEscherichia coli expression system has long been establishedbecause of its effectiveness in characterizing the structure andfunction of exogenously expressed proteins. When eukaryotic membraneproteins are functionally expressed in E. coli, thisorganism can serve as an alternative to eukaryotic host cells. A fewexamples have been reported of functional expression of animal andplant membrane proteins in E. coli. This mini-review describes the following findings: 1) homologousK⁺ transporters exist in prokaryotic cells and ineukaryotic cells; 2) plant K⁺ transporters canfunctionally complement mutant K⁺ transporter genes inE. coli; and 3) membrane structures of plant K⁺ transporters can be elucidated in an E. colisystem. These experimental findings suggest the possibility ofutilizing the E. coli bacterium as an expression system forother eukaryotic membrane transport proteins.

     

Myocardial blood flow heterogeneity in shock and small-volume resuscitation in pigs with coronary stenosis

Kleen, Martin, Martin Welte, Peter Lackermeier, OliverHabler, Gregor Kemming, and Konrad Messmer. Myocardial blood flowheterogeneity in shock and small-volume resuscitation in pigs withcoronary stenosis. J. Appl. Physiol.83(6): 1832-1841, 1997.We analyzed the effects of shock andsmall-volume resuscitation in the presence of coronary stenosis onfractal dimension (D) and spatialcorrelation (SC) of regional myocardial perfusion. Hemorrhagic shockwas induced and maintained for 1 h. Pigs were resuscitated withhypertonic saline-dextran 60 [HSDex, 10% of shed blood volume(SBV)] or normal saline (NS; 80% of SBV). Therapy was continuedafter 30 min with dextran (10% SBV). At baseline, D was 1.39 ± 0.06 (mean ± SE;HSDex group) and 1.34 ± 0.04 (NS group). SC was 0.26 ± 0.07 (HSDex) and 0.26 ± 0.04 (NS). Left anterior descending coronaryartery stenosis changed neither D norSC. Shock significantly reduced D(i.e., homogenized perfusion): 1.26 ± 0.06 (HSDex) and 1.23 ± 0.05 (NS). SC was increased: 0.41 ± 0.1 (HSDex) and 0.48 ± 0.07 (NS). Fluid therapy with HSDex further decreasedD to 1.22 ± 0.05, whereas NS didnot change D. SC was increased by bothHSDex (0.56 ± 0.1) and NS (0.53 ± 0.06). At 1 h afterresuscitation, SC was constant in both groups, andD was reduced only in the NS group(1.18 ± 0.02). We conclude that hemorrhagic shock homogenizedregional myocardial perfusion in coronary stenosis and that fluidtherapy failed to restore this.

     

Effect of crystalloid administration on oxygen extraction in endotoxemic pigs

We asked whethercrystalloid administration improves tissue oxygen extraction inendotoxicosis. Four groups of anesthetized pigs(n = 8/group) received either normalsaline infusion or no saline and either endotoxin or no endotoxin. Wemeasured whole body (WB) and gut oxygen delivery and consumption duringhemorrhage to determine the critical oxygen extraction ratio(ER_O2 crit). Just after onset of ischemia (critical oxygen delivery rate), gut was removed for determination of area fraction of interstitial edema and capillary hematocrit. Radiolabeled microspheres were used todetermine erythrocyte transit time for the gut. Endotoxin decreased WBER_O2 crit(0.82 ± 0.06 to 0.55 ± 0.08, P < 0.05) and gutER_O2 crit(0.77 ± 0.07 to 0.52 ± 0.06, P < 0.05). Unexpectedly, saline administration also decreased WBER_O2 crit (0.82 ± 0.06 to 0.62 ± 0.08, P < 0.05) and gutER_O2 crit (0.77 ± 0.07 to 0.67 ± 0.06, P < 0.05) in nonendotoxin pigs. Saline administration increased thearea fraction of interstitial space (P < 0.05) and resulted in arterial hemodilution(P < 0.05) but not capillaryhemodilution (P > 0.05). Salineincreased the relative dispersion of erythrocyte transit times from0.33 ± 0.08 to 0.72 ± 0.53 (P < 0.05). Thus saline administration impairs tissue oxygen extractionpossibly by increasing interstitial edema or increasing heterogeneityof microvascular erythrocyte transit times.

     

Sleep apnea in obese miniature pigs

Lonergan, Robert P., III, J. Catsby Ware, Richard L. Atkinson, W. Christopher Winter, and Paul M. Suratt. Sleep apnea in obese miniature pigs. J. Appl.Physiol. 84(2): 531-536, 1998.We postulated thatthree extremely obese Yucatan miniature pigs would have more sleepapnea than three nonobese Yucatan miniature pigs. Pigs were studiedwith the use of electroencephalograms, inductance plethysmography,oximetry, expired nasal CO₂, orthermistors. All of the obese pigs, but none of the nonobese pigs, hadboth sleep apnea (8.5, 10.3, and 97.0 in obese pigs vs. 0 apnea + hypopnea/h in all nonobese pigs; P < 0.05) and oxyhemoglobin desaturation episodes during sleep [9.4 ± 3.0 vs. 0 + 0.53 (SD) mean desaturation episodes/h in obese pigsvs. nonobese pigs, respectively; P < 0.05]. Two of the extremely obese pigs had obstructive sleepapnea, whereas the third obese pig had central sleep apnea. We conclude that sleep apnea occurs in extremely obese Yucatan minipigs and suggestthat this animal can be used as a model for sleep apnea in obesity.

     

Hyperpnea-induced bronchoconstriction is dependent on tachykinin-induced cysteinyl leukotriene synthesis

Yang, X. X., W. S. Powell, M. Hojo, and J. G. Martin.Hyperpnea-induced bronchoconstriction is dependent ontachykinin-induced cysteinyl leukotriene synthesis. J. Appl. Physiol. 82(2): 538-544, 1997.The purposeof the study was to test the hypothesis that tachykinins mediatehyperpnea-induced bronchoconstriction indirectly by triggeringcysteinyl leukotriene (LT) synthesis in the airways. Guinea pigs(350-600 g) were anesthetized with xylazine and pentobarbital sodium and received hyperpnea challenge (tidal volume 3.5-4.0 ml,frequency 150 breaths/min) with either humidified isocapnic gas(n = 6) or dry gas(n = 7). Dry gas challenge wasperformed on animals that received MK-571(LTD₄ antagonist; 2 mg/kg iv; n = 5), capsaicin(n = 4), neurokinin (NK) antagonists[NK₁ (CP-99994) + NK₂ (SR-48968) (1 mg/kg iv);n = 6], or theH₁ antihistamine pyrilamine (2 mg/kg iv; n = 5). We measured thetracheal pressure and collected bile for 1 h before and 2 h afterhyperpnea challenge. We examined the biliary excretion of cysteinylLTs; the recovery of radioactivity in bile after instillation of 1 µCi [³H]LTC₄intratracheally averaged 24% within 4 h(n = 2). The major cysteinyl LTidentified was LTD₄ (32% recoveryof radioactivity). Cysteinyl LTs were purified from bile of animalsundergoing hyperpnea challenge by using reverse-phase high-pressureliquid chromatography and quantified by radioimmunoassay. There was asignificant increase in the peak value of tracheal pressure afterchallenge, indicating bronchoconstriction in dry gas-challenged animalsbut not after humidified gas challenge. MK-571, capsaicin, and NKantagonists prevented the bronchoconstriction; pyrilamine didnot. Cysteinyl LT levels in the bile after challenge weresignificantly increased from baseline in dry gas-challenged animals(P < 0.05) and were higher than inthe animals challenged with humidified gas or dry gas-challengedanimals treated with capsaicin or NK antagonists (P < 0.01). The results indicatethat isocapnic dry gas hyperpnea-induced bronchoconstriction is LTmediated and the role of tachykinins in the response is indirectthrough release of LTs. Endogenous histamine does not contribute to theresponse.

     

Antithrombin reduces leukocyte adhesion during chronic endotoxemia by modulation of the cyclooxygenase pathway

Antithrombin (AT) isknown as the most important natural inhibitor of thrombin activity andhas been shown to improve distinct clinical parameters during thecourse of septic (endotoxin)-induced multiple organ dysfunction. Wehypothesized that AT acts by inhibiting leukocyte activation andmicrovascular injury via the promotion of endothelial release ofPGI₂, and therefore, we studied the effects of AT onleukocyte/endothelial cell interaction and microvascular perfusionduring endotoxemia. In a skinfold preparation of Syrian hamsters,severe endotoxemia was induced by repeated administration of endotoxinintravenously [lipopolysaccharide (LPS), Escherichia coli,2 mg/kg] at 0 and 48 h. AT (250 IU/kg) was administered intravenously at 0, 24, and 48 h (n = 6, ATgroup). In control animals (n = 5, control), LPS wasgiven without AT supplementation. By intravital fluorescencemicroscopy, leukocyte-endothelial cell interaction and functionalcapillary density (FCD; measure of capillary perfusion) were analyzedduring a 72-h period after the first LPS injection. AT significantlyattenuated LPS-induced arteriolar and venular leukocyte adherence afterboth the first and the second LPS injection [P < 0.01, measures analysis of variance (MANOVA)]. In parallel, AT waseffective in preventing LPS-induced depression of FCD after the firstand the second LPS administration (P < 0.05, MANOVA).By pretreatment with the cyclooxygenase inhibitor indomethacin(n = 6), effects of AT on leukocyte adherence and FCDwere found completely abolished. Thus our study indicates that ATexerts its beneficial effects in endotoxemia by reducing leukocyte-endothelial cell interaction and microvascular perfusion failure probably via liberation of prostacyclin from endothelial cells.

     

Cyclooxygenase inhibition potentiates the renal vascular response to endothelin-1 in humans

Vascular endothelin-receptor stimulation resultsin vasoconstriction and concomitant production of the vasodilatorsprostaglandin I₂ and nitric oxide.The vascular effects of cyclooxygenase (COx) blockade (diclofenacintravenously) and the subsequent vasoconstrictor response toendothelin-1 (ET-1) infusion 30 min after diclofenac were studied inhealthy men. With COx blockade, cardiac output (7%) and splanchnic(14%) and renal (12%) blood flows fell (all P < 0.001). Splanchnic blood flowreturned to basal value within 30 min. Mean arterial blood pressureincreased (4%, P < 0.001). Splanchnic glucose output fell (22%,P < 0.01). Subsequent ET-1 infusioncaused, compared with previous ET-1 infusion without COx blockade (G. Ahlborg, E. Weitzberg, and J. M. Lundberg. J. Appl.Physiol. 77: 121-126, 1994; E. Weitzberg, G. Ahlborg, and J. M. Lundberg. Biochem. Biophys. Res.Commun. 180: 1298-1303, 1991; E. Weitzberg, G. Ahlborg, and J. M. Lundberg. Clin.Physiol. (Colch.) 13: 653-662, 1993),the same increase in mean arterial blood pressure (4%), decreases incardiac output (13%) and splanchnic blood flow (38%), but nosignificant change in splanchnic glucose output. Renal blood flowreduction was potentiated (33 ± 3 vs. 23 ± 2%,P < 0.02), with a total reductioncorresponding to 43 ± 3%(P < 0.01 vs. 23 ± 3%). Weconclude that COx inhibition induces renal and splanchnicvasoconstriction. The selectively increased renal vascularresponsiveness to ET-1 emphasizes the importance of endogenousarachidonic acid metabolites (i.e., prostaglandin I₂) to counteract ET-1-mediatedrenal vasoconstriction.

     

PAF increases vascular permeability without increasing pulmonary arterial pressure in the rat

In vivo pulmonary arterialcatheterization was used to determine the mechanism by whichplatelet-activating factor (PAF) produces pulmonary edema inrats. PAF induces pulmonary edema by increasing pulmonarymicrovascular permeability (PMP) without changing the pulmonarypressure gradient. Rats were cannulated for measurement of pulmonaryarterial pressure (Ppa) and mean arterial pressure. PMP wasdetermined by using either in vivo fluorescent videomicroscopy or theex vivo Evans blue dye technique. WEB 2086 was administeredintravenously (IV) to antagonize specific PAF effects. Threeexperiments were performed: 1) IV PAF, 2) topical PAF, and 3) Escherichia coli bacteremia. IV PAFinduced systemic hypotension with a decrease in Ppa. PMP increasedafter IV PAF in a dose-related manner. Topical PAF increased PMP butdecreased Ppa only at high doses. Both PMP (88 ± 5%) and Ppa(50 ± 3%) increased during E. coli bacteremia.PAF-receptor blockade prevents changes in Ppa and PMP after bothtopical PAF and E. coli bacteremia. PAF, which has beenshown to mediate pulmonary edema in prior studies, appears to act inthe lung by primarily increasing microvascular permeability. Thepresence of PAF might be prerequisite for pulmonary vascularconstriction during gram-negative bacteremia.

     

rG-CSF reduces endotoxemia and improves survival during E.coli pneumonia

Freeman, Bradley D., Zenaide Quezado, Fabrice Zeni, CharlesNatanson, Robert L. Danner, Steven Banks, Marcello Quezado, YvonneFitz, John Bacher, and Peter Q. Eichacker. rG-CSF reduces endotoxemia and improves survival during E. coli pneumonia. J. Appl.Physiol. 83(5): 1467-1475, 1997.We investigatedthe effects of recombinant granulocyte colony-stimulating factor(rG-CSF) during canine bacterial pneumonia. Beagles with chronictracheostomies received daily subcutaneous rG-CSF (5 µg/kg body wt)or placebo for 14 days, beginning 9 days before intrabronchialinoculation with E. coli. Animalsreceived antibiotics and fluid support; a subset received humidifiedoxygen (fractional inspired O₂0.40). Compared with controls, rG-CSF increased circulating neutrophil counts (57.4 vs. 11.0 × 10³/mm³,day 1 after infection;P = 0.0001), decreased plasmaendotoxin (7.5 vs. 1.1 EU/ml at 8 h; P < 0.01) and serum tumor necrosis factor- (3,402 vs.729 pg/ml at 2 h; P = 0.01) levels,and prolonged survival (relative risk of death = 0.45, 95% confidenceinterval 0.21-0.97; P = 0.038).Also, rG-CSF attenuated sepsis-associated myocardial dysfunction(P < 0.001). rG-CSF had no effect onpulmonary function or on blood and lung bacteria counts (allP = not significant). Other animalschallenged with endotoxin (4 mg/kg iv) after similar treatment withrG-CSF had lower serum endotoxin levels (7.62 vs. 5.81 log EU/ml at 6 h; P < 0.01) and less cardiovasculardysfunction (P < 0.05 to < 0.002)but similar tumor necrosis factor- levels (P = not significant) compared withcontrols. Thus prophylactic rG-CSF sufficient to increase circulatingneutrophils during bacterial pneumonia may improve cardiovascularfunction and survival by mechanisms that in part enhance the clearanceof bacterial toxins but do not improve lung function.

     

Exercise causes blood glutathione oxidation in chronic obstructive pulmonary disease: prevention by O2 therapy

Viña, José, Emilio Servera, Miguel Asensi, JuanSastre, Federico V. Pallardó, José A. Ferrero, JoséGarcía-de-la-Asunción, Vicente Antón, and JulioMarín. Exercise causes blood glutathione oxidation inchronic obstructive pulmonary disease: prevention by O₂therapy. J. Appl. Physiol. 81(5):2199-2202, 1996.The aim of the present study was to determinewhether glutathione oxidation occurs in chronic obstructive pulmonarydisease (COPD) patients who perform exercise and whether this could beprevented. Blood glutathione red-ox ratio [oxidized-to-reducedglutathione (GSSG/GSH)] was significantly increased when patientsperformed exercise for a short period of time until exhaustion. Theirresting blood GSSG/GSH was 0.039 ± 0.008 (SD)(n = 5), whereas after exercise itincreased to 0.085 ± 0.019, P < 0.01. Glutathione oxidation associated with exercise was partiallyprevented by oxygen therapy (resting value: 0.037 ± 0.014, n = 5; after exercise: 0.047 ± 0.016, n = 5, P < 0.01). We conclude that lightexercise causes an oxidation of glutathione in COPD patients, which canbe partially prevented by oxygen therapy.

     

Intratracheal instillation of a novel NO/nucleophile adduct selectively reduces pulmonary hypertension

Brilli, Richard J., Brian Krafte-Jacobs, Daniel J. Smith,Dominick Roselle, Daniel Passerini, Amos Vromen, Lori Moore, CsabaSzabó, and Andrew L. Salzman. Intratracheal instillation ofa novel NO/nucleophile adduct selectively reduces pulmonary hypertension. J. Appl. Physiol. 83(6):1968-1975, 1997.We examined the pulmonary and systemichemodynamic effects of administering soluble nitric oxide (NO) donorcompounds (NO/nucleophile adducts, i.e., NONOates) directly into thetrachea of animals with experimentally induced pulmonary hypertension.Steady-state pulmonary hypertension was created by using thethromboxane agonist U-46619. Yorkshire pigs were randomly assigned toone of four groups: group 1,intratracheal saline (control; n = 8);group 2, intratracheal sodiumnitroprusside (n = 6);group 3, intratracheal ethylputreanineNONOate (n = 6); andgroup 4, intratracheal2-(dimethylamino)-ethylputreanine NONOate (DMAEP/NO;n = 6). Pulmonary and systemichemodynamics were monitored after drug instillation.Group 4 had significant reductions in pulmonary vascular resistance index (PVRI) at all time points comparedwith steady state and compared with group1 (P < 0.05), whereas systemic vascular resistance index did not change. The meanchange in mean pulmonary arterial pressure in group4 was 33.1 ± 1.2% compared with +6.4 ± 1.3% in group 1 (P < 0.001), and the mean change inmean arterial pressure was 9.3 ± 0.7% compared with acontrol value of 0.9 ± 0.5%(P < 0.05). Groups 2 and 3 hadsignificant decreases in both PVRI and systemic vascular resistanceindex compared with steady state and with group1. In conclusion, intratracheal instillation of apolar-charged tertiary amine NONOate DMAEP/NO results in the selectivereduction of PVRI. Intermittent intratracheal instillation of selectiveNONOates may be an alternative to continuously inhaled NO in thetreatment of pulmonary hypertension.

     

Effects of edema on small airway narrowing

Wagner, Elizabeth M. Effects of edema on small airwaynarrowing. J. Appl. Physiol. 83(3):784-791, 1997.Numerous mediators of inflammation have beendemonstrated to cause airway microvascular fluid and proteinextravasation. That fluid extravasation results in airway wall edemaleading to airway narrowing and enhanced reactivity has not beenconfirmed. In anesthetized, ventilated sheep(n = 30), airway vascularfluid extravasation was induced by infusing bradykinin(10⁶ M) through acannulated, blood-perfused bronchial artery. Airway wall edema andluminal narrowing were determined morphometrically. Airway reactivityto methacholine (MCh; 10 µg/ml, intrabronchial artery) was determinedby measuring conducting airway resistance (Raw) by forced oscillation.Raw measurements were made and lung lobes were excised and quick frozenbefore or after a 1-h bradykinin infusion. In 10 airways per lobe(range 0.2- to 2.0-mm relaxed diameter), wall area occupied 32 ± 2% (SE) of the total normalized airway area(n = 9). Bradykinin infusion increasedwall area to 42 ± 5% (P = 0.02);luminal area decreased by <5%; and smooth muscle perimeter, ameasure of smooth muscle constriction, was not altered(n = 5). Raw showed nochange from baseline (1.4 ± 0.4 cmH₂O · l¹ · s)after bradykinin infusion (n = 10).During MCh challenge, Raw increased by 3.2 ± 04 cmH₂O · l¹ · s,and this change did not differ after administration of bradykinin. MChchallenge caused similar decreases in smooth muscle perimeter (10%)and luminal area (72 vs. 68%) before and after bradykinin infusion.However, the time constant of recovery of Raw from MCh constriction wasincreased from control (40 ± 3 s) to 57 ± 10 s after bradykinininfusion (P = 0.03). When lung lobeswere excised at the same time after MCh challenge was terminated(n = 5), luminal area was greaterbefore bradykinin infusion than after (86 vs. 78%;P = 0.007), as was smooth muscleperimeter. The results of this study demonstrate that airway wall edemalimits relaxation after induced constriction rather than enhancingconstriction.

     

Supercritical fluid-aerosolized vitamin E pretreatment decreases leak in isolated oxidant-perfused rat lungs

Hybertson, Brooks M., Roger P. Kitlowski, Eric K. Jepson,and John E. Repine. Supercritical fluid-aerosolized vitamin Epretreatment decreases leak in isolated oxidant-perfused rat lungs.J. Appl. Physiol. 84(1): 263-268, 1998.We hypothesized that direct pulmonary administration ofsupercritical fluid-aerosolized (SFA) vitamin E would decrease acuteoxidative lung injury. We previously reported that rapid expansion ofsupercritical CO₂ formedrespirable particles of vitamin E and that administering SFA vitamin Eto rats increased lung vitamin E levels and decreased neutrophil-mediated lung leak. In the present investigation, we foundthat pretreatment with SFA vitamin E protected isolated rat lungsagainst the oxidant-induced lung leak caused by perfusion with xanthineoxidase (XO) and purine, an enzyme system that generates superoxideanion () and hydrogenperoxide. SFA vitamin E droplets were 0.7-3 µm in diameter, andinhalation of the airborne droplets for 30 min deposited ~55 µg ofvitamin E in rat lungs. Isolated rat lungs perfused with XO (0.02 U/ml) and purine (10 mM) gained more weight (1.75 ± 0.12 g,n = 8), retained more Ficoll(11.5 ± 1.2 mg/left lung,n = 7), and accumulated more Ficoll intheir lung lavages (700 ± 146 µg/ml,n = 8) than control lungs [0.25 ± 0.06 g (n = 10), 6.2 ± 1.2 mg/left lung (n = 9), and 141 ± 31 µg/ml (n = 8), respectively,P < 0.05]. In contrast,isolated lungs from rats that were pretreated with SFA vitamin E haddecreased (P < 0.05) weight gains(0.32 ± 0.06 g, n = 7), Ficollretentions (3.3 ± 1.1 mg/left lung,n = 7), and lung lavage Ficollconcentrations (91 ± 26 µg/ml,n = 6) after perfusion with XO andpurine compared with isolated lungs from control rats perfused with XOand purine. This protective effect was not observed in rat lungs givensham treatments (CO₂ alone orvitamin E acetate aerosolized with supercriticalCO₂). Our results suggest thatdirect pulmonary supplementation of vitamin E decreases susceptibilityto vascular leakage caused by XO-derived oxidants.