Dynamics of organ blood flow in rats in postnatal ontogenesis

In the 4-, 13-, 30-, and 65–90-day old anestetized Wistar rats (8–15 rats in each group) the voluminous blood flow rate was measured in liver, kidney, small intestine wall, and in the predominantly white gracilis muscle of femur. A LAKK-01 laser-Doppler flowmeter and its cutaneous (for kidney) and needle (for other organs) probes were used; they provided estimation of blood flow to the tissue depth of about 1 mm. It has been found that the blood flow rates (per organ mass unit) fall in liver, intestine, and even more in muscle, whereas increase in kidney, particularly for the first month of life. Calculations show that in adult rats as compared with the 4-day old pups (with their mass exceeding 22 times) the blood flow to muscle, liver, intestine, and kidney should rise (with taking into account the increase of mass of the organs) 14, 17, 18, and 43 times, respectively.     

Combination of microdialysis and glucosensor permits continuous (on line) SC glucose monitoring in a patient operated device. II. Evaluation in animals.

The microdialysis technique was used for following the glucose content of the extracellular subcutaneous (SC) fluid under varying blood glucose levels in rats. The glucose content in the microdialysis perfusion fluid was continuously analyzed by means of the measuring flow chamber of an ex vivo glucose monitor. In six ChBB rats blood glucose levels were varied between 40 mg/dl and 575 mg/dl by intravenous (IV) infusion of glucose and by SC injections of insulin, respectively. After a running-in period of about half an hour, the glucose content in the perfusion fluid was closely related to the blood glucose concentration (r > 0.92) up to a time period of 6 hrs. The "relative recovery" rate of glucose by the microdialysis probe in the SC tissue varied within the 6 experimental sessions. The relative recovery rate could be shown to be not dependent on the absolute blood glucose levels in the individual rat within the glucose concentration range tested.     

"调神畅志"针刺法对帕金森伴便秘模型大鼠结肠组织5-HT4R及CaM-MLCK信号通路影响的研究

摘要 目的：探讨"调神畅志"针刺法对帕金森伴便秘(Parkinson''s disease with constipation)模型大鼠结肠组织中5-羟色胺4受体（5-HT4R）及钙调蛋白（CaM）-肌球蛋白轻链激酶（MLCK）信号通路影响的研究,并探讨其可能作用机制。方法：采用随机数字表将60只大鼠分为空白组、假手术组、模型组、西药组、常规针刺组、调神畅志针刺组,每组10只。模型组、常规针刺组、调神畅志针刺组颈背部皮下注射鱼藤酮的方法制造PDD大鼠模型,并用阿扑吗啡（APO）诱导检测。常规针刺组选取天枢、足三里、上巨虚及舞蹈震颤控制区,接电针,连续波频率15Hz,刺激强度2 mA,留针30分钟,1日1次,连续4周;调神畅志针刺组：选取王顺教授 " 调神畅志 " 三六九针法,百会透太阳、中脘、气海、足三里、太冲,采用连续波,头针频率45Hz,腹针频率30Hz,肢体针频率15Hz（体现调神畅志三六九针法的头针重、腹针中、四肢针轻的量化刺激）,刺激强度约2 mA,留针30 min,1日1次,连续4周;西药组采用美多芭、莫沙必利每日灌胃,连续治疗4周;模型组、假手术组：每日2 mL生理盐水灌胃,连续4周;空白组不予处理。采用Western blot法检测各组近端结肠组织中5-HT4R、CaM及MLCK蛋白表达以及含量水平。结果：与空白组相比,模型组大鼠近端结肠组织中5-HT4R、CaM及MLCK蛋白表达水平显著降低(P<0.01),与模型组比较,三个治疗组（西药组、常规针刺组、调神畅志针刺组）近端结肠组织5-HT4R、CaM及MLCK蛋白表达水平显著升高(P<0.01)。与常规针刺组相比,调神畅志组5-HT4R、CaM及MLCK蛋白表达水平明显升高(P<0.05)。结论：针刺可改善PD伴便秘大鼠模型便秘症状,且调神畅志针刺组优于常规针刺组,其作用机理可能通过调节大鼠结肠组织中5-HT4R蛋白表达以及激活CaM-MLCK信号通路来实现的。     

Real-time cortical cerebral blood flow follow-up in conscious,freely moving rats by laser Doppler flowmetry

This article describes a laser Doppler flowmetry (LDF) system that enables repeated measurements and thereby long-term followup of cortical cerebral blood flow (CBF) in awake and freely moving rats. The system consists of a specially designed flow probe adapter, a flow probe connector, and a LDF flow probe, which may thereby rotate through its own axis. During the experiment, the flow adapter is permanently mounted onto the rat's skull bone. A thin layer of skull bone is left intact at the site for cortical CBF measurements. The probe connector and the flow probe may be repeatedly detached and remounted to the adapter, which allows for cortical cerebral blood flow recording from exactly the same anatomical location. The laser Doppler flowmetry system enables stable cortical CBF recordings in the conscious rat while it moves freely in a bowl cage.     

Reaction velocities in vivo: standardization of kinetic "constants" by correction for blood flow

1. The results of kinetic studies in vitro are difficult to apply to metabolic reactions in vivo. 2. In living vertebrates reaction rates are usually first-order and for a particular reaction the rate "constant", k, varies with the several thousand-fold variations in metabolic rate. 3. Therefore, in the kinetic equation (formula: see text) since K varies with metabolic rate, Vmax and/or Km will aslo vary. 4. However, reaction rates for a series of different substrates were similar in animals varying widely in metabolic rate if corrections were made for differences in blood flow. 5. The observation that metabolic rate (reaction rate) is directly dependent on blood flow (Coulson et al., 1977) allowed derivation of new kinetic constants which were valid in vivo. 6. Introduction of a flow term into the observed first-order equations yields an "affinity constant", K, or a "flow constant", KF, somewhat analogous to Km, which allows one to predict reaction rates in animals of different metabolic rates. 7. The defining equations are (formula: see text) where V = reaction velocity in mmol/hr/kg tissue, [S] = millimolar substrate concentration in the blood, k = In 2/tau (tau the half-life) and F = blood flow in 1/hr/kg tissue. 8. Thus, K = k/F = 1/KF. The KF's for the initial step in the degradation of 17 amino acids in rats, dogs, lizards, turtles and alligators were similar, demonstrating the similarity of enzyme affinities in different species.     

Endometrial blood flow in rats.

The endometrial blood flow was measured in rats by injections of 85Kr saline into aorta and measurements of the clearance of the radioactivity by a Geiger-Müller probe situated in the uterine lumen. Estrus and diestrus were determined by vaginal smears. The endometrial blood flow was found to be 0.88 +/- 0.08 (mean +/- SEM) ml/g tissue/min in estus and 1.60 +/- 0.15 mg/g/min in diestrus. The experiment indicates that the endometrial blood flow and the total uterine blood flow change in opposite directions during the estrous cycle.     

Static and dynamic imaging of alveoli using optical coherence tomography needle probes

Imaging of alveoli in situ has for the most part been infeasible due to the high resolution required to discern individual alveoli and limited access to alveoli beneath the lung surface. In this study, we present a novel technique to image alveoli using optical coherence tomography (OCT). We propose the use of OCT needle probes, where the distal imaging probe has been miniaturized and encased within a hypodermic needle (as small as 30-gauge, outer diameter 310 μm), allowing insertion deep within the lung tissue with minimal tissue distortion. Such probes enable imaging at a resolution of ～12 μm within a three-dimensional cylindrical field of view with diameter ～1.5 mm centered on the needle tip. The imaging technique is demonstrated on excised lungs from three different species: adult rats, fetal sheep, and adult pigs. OCT needle probes were used to image alveoli, small bronchioles, and blood vessels, and results were matched to histological sections. We also present the first dynamic OCT images acquired with an OCT needle probe, allowing tracking of individual alveoli during simulated cyclical lung inflation and deflation.     

Absence of increased oxygen consumption in brown adipose tissue of rats exhibiting "cafeteria" diet-induced thermogenesis

Young male Sprague-Dawley rats were induced to overeat (approximately 45%) by provision of a "cafeteria" (CAF) diet of palatable human foods. Normophagic rats fed a commercial chow or a semisynthetic diet served as controls. The CAF rats exhibited (a) the reduced food efficiency and the propranolol-inhibitable elevation in resting metabolic rate (resting VO2) that are indicative of a facultative diet-induced thermogenesis (DIT) by which excess energy gain is resisted, and (b) certain changes in brown adipose tissue (BAT) that are among those taken as evidence for BAT as the effector of DIT, e.g., increased protein content and increased mitochondrial binding of GDP. To assess directly and quantitatively the contribution by BAT to the elevation in VO2 (apparent DIT) of the CAF rats, BAT O2 consumption was determined (Fick principle) from measurements of tissue blood flow (microsphere method) and the arteriovenous difference in blood O2 across interscapular BAT (IBAT). To obtain the measurements, the animals were fitted under halothane anesthesia with vascular cannulas for intraventricular injection of microspheres and sampling of arterial blood and the venous effluent of IBAT. After recovery from anesthesia and rewarming to normal body temperature the animals were placed singly in a temperature-controlled metabolic chamber and the measurements, which also included determination of resting VO2, were made 1.5-2 h later about 11:30 h. As determined from measurements made at 28 degrees C (thermoneutrality) mean values of resting VO2 for the cannulated rats were unchanged from those of intact (unoperated) CAF or control rats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Needle age dependence of photosynthesis along a light gradient within an <Emphasis Type="Italic">Abies alba</Emphasis> crown

Age and shade effects on needle structure and photosynthesis were determined within a lower part of Abies alba crown along a horizontal increasing gradient of branches self-shading. It was hypothesized that a decrease in net CO₂ assimilation rate with increasing needles’ age would be related to: (1) structural age-related changes in needles, (2) reduction of stomatal conductance, (3) nitrogen translocation from old to young needles, and (4) decrease in efficiency of photochemical processes. Leaf mass-to-area ratio increased non-linearly with needle age. In a needle cross section, distance between the vascular bundles decreased, and height of palisade parenchyma cells increased with age. The structural changes observed in our study might lead to an increase in internal resistance to CO₂ with greater needle age. Total needle nitrogen concentration linearly decreased with age due to dilution and/or translocation to younger needles. When expressed per needle area, nitrogen content was reduced in 6-year-old needles compared with younger ones. Net CO₂ assimilation rate per needle area decayed and was accompanied by a decrease in transpiration and water and photosynthetic nitrogen use efficiency. Old needles maintained high photochemical efficiency which compensated to some extent for light deficit in their micro-light environments. Our results have suggested that there is a mechanism controlling the relation between efficiency of light and dark photosynthetic processes along the needle age and shade gradient in A. alba crown.     

Dynamics of coronary circulation in rats]

The blood flow velocities in left anterior descending coronary artery and ascending aorta have been measured in anesthetized rats by high frequency Doppler technique. The measurement of coronary blood flow velocity by miniature ultrasonic probe (2.0 x 1.5 mm) was performed through myocardial surface. Two different forms of coronary blood flow curves were recorded. These forms of the curves depend on the value of the coronary blood flow velocity and are connected with the ascending aorta blood flow velocity. The dynamics of the coronary blood flow reactions under coronary artery occlusion and asphyxia in the rat is similar to the one in the cat and the dog, but less expressive. In experiments with vasodilators the direct dependence between linear and volume coronary artery velocities under the measurement through myocardial surface was found.     

The use of an "internal standard" for control of the recovery in microdialysis

Microdialysis of intravenously injected theophylline in blood and in lung tissue was performed in two rats during anaesthesia. The recovery (dialysate extraction fraction) in blood was greater than the recovery in lung tissue and there was a change in recovery with time both in blood and in lung. The concentrations of theophylline in the dialysates were corrected for the recovery using caffeine as an "internal standard" in the perfusate as well as tritiated water injected into the rats. There was excellent agreement between the two different methods. Furthermore, the corrected concentration of unbound theophylline in the blood was in accordance with the simultaneously measured total concentration of theophylline in plasma when binding to plasma proteins was taken into account. The conclusion is that an "internal standard" for correction of the recovery is a useful method to approach the true concentrations of compounds in the extracellular water. The "internal standard" must be as equal as possible to the substance of interest.     

Changes in autoregulation of coronary blood flow in rats with various sensitivity to stress

The purpose of work: study of a role of endothelial nitric oxide in development of stress-induced changes in autoregulation of coronary blood flow in rats with various types of behaviour. The experiments were performed on isolated hearts of female-rats, in the "open field" test, depending on the type of impelling and searching activity of animals subdivided into two groups: "active" and "passive". After a 6-hour immobilization stress only in "passive" rats an increase of volumetric velocity of coronary flow; a decrease of an autoregulation index, coronary reserve against the background of intravascular pressure reduction, were found out. The blockade of nitric oxide synthesis in this group completely eliminated the stress-induced decrease of coronary vascular tone and essentially limited the caused by stress dissociation of coronary flow and the contractility function of the myocardium. In blood plasma of "passive" animals the nitrite/nitrate contents was by 55% more than of the "active" rats. After the transferred stress, in "passive" animals the nitrite/nitrate concentration in blood plasma increased by 29% and in "active" rats--by 136%; the absolute values, however, did not differ between the groups. Thus the autoregulation of coronary flow seems to be subject to action of stress in the rats showing a "passive" type of behaviour in the test "open field", and practically does not change in "active" animals; secondly, in spite of the fact that the stress-induced amplification of NO-producing function andothelium of coronary blood vessels is stereotyped in different rats, in "passive" rats, apparently, sensitivity of coronary vessels to nitric oxide is higher than at "active" those.     

Blood sampling from the cranial vena cava in the Norway rat (Rattus norvegicus)

This paper describes blood sampling from the cranial vena cava (CVC) in the Norway rat. In order to limit stress, the blood sampling should be done under short-term inhalation anaesthesia, for example, an oxygen/isoflurane mixture. The injection site is just cranial to the first rib, 0.3-0.8 cm lateral to the manubrium when the animal is in dorsal recumbency. The needle, attached to a syringe, is inserted at 30 degrees in the direction of the opposite femoral head. After penetration of the skin, negative pressure is developed in the syringe and the insertion of the needle is continued for another 0.2-1 cm in the given direction until blood begins to flow. The amount of blood sampled ranges from 0.8 to 2.5 mL depending on the body weight of the patient. A trial on 50 rats aged 5-24 months included 25 rats sampled once, eight rats sampled twice with an interval of seven days, 11 rats sampled twice with an interval of three weeks and four rats sampled four times with intervals of four weeks--a total of 87 blood samplings. The serious complications quoted in association with blood sampling from the CVC in other experimental animals (vascular lacerations, heart puncture, serious haemorrhage, tracheal and throat trauma) were not observed in our study. There were only four blood samplings (4.5%) with mild haemorrhage from the injection site, due to erroneous sampling from the jugular vein.     

Cardiovascular responses to V1-vasopressinergic antagonism in conscious versus anesthetized rats

Experiments were performed to compare the possible effect of endogenous arginine vasopressin on renal hemodynamics between anesthetized, surgically stressed rats and conscious rats. Animals were instrumented with arterial and venous catheters as well as with a pulsed Doppler flow probe on the left renal artery. The rats were studied under the following conditions: (1) conscious and unrestrained; (2) anesthetized only; (3) anesthetized with minor surgical stress; and (4) anesthetized with major surgical stress. Two anesthetic agents were also compared, a mixture of ketamine (110 mg/kg i.m.) and acepromazine (1 mg/kg i.m.), and sodium pentobarbital (50 mg/kg i.p.). Baseline mean arterial blood pressure was significantly higher in pentobarbital-anesthetized rats following surgical stress compared with conscious animals, but blood pressure was not affected by ketamine-acepromazine anesthesia. After baseline measurements of blood pressure, heart rate, and renal blood flow, a specific V1-vasopressinergic antagonist (d(CH2)5Tyr(Me) arginine vasopressin, 10 mg/kg i.v.) was administered to each group. Mean arterial blood pressure, heart rate, and renal blood flow were monitored for an additional 15 min. Mean arterial blood pressure and renal blood flow decreased after V1 antagonism in ketamine-acepromazine-anesthetized rats with major surgical stress, but were not affected in pentobarbital-anesthetized animals. Heart rate and renal vascular resistance were not affected following V1 blockade with either anesthetic agent. These data suggest that arginine vasopressin plays a role in maintaining blood pressure and renal perfusion in ketamine-acepromazine-anesthetized rats following surgical stress, but does not have a significant effect on renal hemodynamics under pentobarbital anesthesia.     

Local cerebral blood flow following the intrastriatal administration of vasoactive intestinal peptide or peptide histidine isoleucine in the rat

The effect of the intrastriatal microinjection of either vasoactive intestinal peptide (VIP) or a related peptide-peptide histidine isoleucine (PHI)-on local cerebral blood flow in the striatum was examined using iodo[14C]antipyrine quantitative autoradiography. In 37 rats, an injection needle was inserted into a chronically implanted guide cannula and 1 microliter of vehicle, VIP or PHI was injected into the striatum. Blood flow in sham controls was reduced by 15% in proximity to the injection site, when compared with blood flow in the contralateral uninjected control side (P less than 0.01). Similarly, following PHI administration (20 pmol), blood flow in the striatum was reduced by 14% when compared to that contralaterally (P less than 0.02). In contrast, following VIP administration (20 pmol), blood flow in proximity to the injection site was increased compared to flow in the contralateral striatum in 4/8 animals with the mean flow being elevated by 10% (n.s.) compared to blood flow contralaterally. VIP and PHI had similar effects on local cerebral glucose utilization in the caudate nucleus, their response being equivalent to that of sham animals. These experiments suggest that VIP and PHI have a differential influence on the microvasculature of the caudate nucleus, with VIP but not PHI mediating cerebrovascular dilation.     

Skin blood flow in the Wistar-Kyoto rat and the spontaneously hypertensive rat

• 1.1. Using laser Doppler techniques in man, we have previously demonstrated differences in skin blood flow properties at sites with primarily nutritive (NUTR) perfusion, such as the elbow or knee, as compared to sites such as the finger pulp, with predominantly arteriovenous anastomotic (AVA) perfusion.
• 2.2. Basal and heat stimulated flow is greater at AVA sites. In man, blood pressure changes are reflected primarily by changes at AVA rather than NUTR sites.
• 3.3. These blood pressure induced changes affect the red blood cell velocity (VEL) component at AVA sites more than microvascular volume (VOL).
• 4.4. Given these findings in man, we decided to compare skin blood flow properties in a suitable animal model.
• 5.5. We chose the Wistar-Kyoto (WKY) and Spontaneously Hypertensive Rat (SHR) strains, in view of the marked difference in systemic blood pressure in these two related strains.
• 6.6. Skin blood flow varied considerably at different skin sites in the rats. Skin sites with hair covering, on the back and at the base of the tail, showed low basal and heat stimulated blood flow.
• 7.7. In contrast, the plantar surface of the paw behaved similarly to the finger or toe pulps in man, with 3–4-fold higher basal flow than the hair covered areas and a 7–8-fold rise with local heating to 44°C.
• 8.8. Furthermore, there was a 25% greater blood flow at the plantar paw surface in the SHR rats as compared to the WKY rats, corresponding to the 25% higher systemic blood pressure in these animals.
• 9.9. The heat induced increase in flow at the plantar surface of the paw was primarily a result of a marked increase in VEL rather than VOL.
• 10.10. The higher flow at this site in SHR as compared to WKY rats was likewise ascribable to an increase in VEL, VOL being equivalent in the two strains.

     

Autoregulation of renal medullary blood flow in rabbits

We examined the extent of renal medullary blood flow (MBF) autoregulation in pentobarbital-anesthetized rabbits. Two methods for altering renal arterial pressure (RAP) were compared: the conventional method of graded suprarenal aortic occlusion and an extracorporeal circuit that allows RAP to be increased above systemic arterial pressure. Changes in MBF were estimated by laser-Doppler flowmetry, which appears to predominantly reflect erythrocyte velocity, rather than flow, in the kidney. We compared responses using a dual-fiber needle probe held in place by a micromanipulator, with responses from a single-fiber probe anchored to the renal capsule, to test whether RAP-induced changes in kidney volume confound medullary laser-Doppler flux (MLDF) measurements. MLDF responses were similar for both probe types and both methods for altering RAP. MLDF changed little as RAP was altered from 50 to >or=170 mmHg (24 +/- 22% change). Within the same RAP range, RBF increased by 296 +/- 48%. Urine flow and sodium excretion also increased with increasing RAP. Thus pressure diuresis/natriuresis proceeds in the absence of measurable increases in medullary erythrocyte velocity estimated by laser-Doppler flowmetry. These data do not, however, exclude the possibility that MBF is increased with increasing RAP in this model, because vasa recta recruitment may occur.     

Age-induced changes in pancreatic islet blood flow: evidence for an impaired regulation in diabetic GK rats

The present study aimed to compare longitudinal variations in islet blood perfusion in rats with different degrees of impairment of glucose metabolism. For this purpose, mildly diabetic Goto-Kakizaki (GK) rats, glucose intolerant F(1) hybrids of GK and Wistar (W) rats (H), and control W rats were examined at 5 wk, 12 wk, or 1 yr of age, using the microsphere technique for blood flow measurements. W rats showed progressively increasing islet blood flow (IBF) throughout the experiment. Both GK and H rats demonstrated increasing IBF between 5 and 12 wk. However, H rats showed no further increment in IBF at 1 yr, whereas GK rats displayed a pronounced decrease in IBF between 12 wk and 1 yr of age. The augmented IBF seen in older W rats may constitute an adaptation to the increasing demand for insulin secretion in aging rats. The inability to adapt to the increased demand for insulin secretion by upregulation of islet blood flow could contribute to the progressive deterioration of glucose metabolism seen in the aging GK rat.     

Status of the "dead point" of blood flow in anastomoses of superficial cerebral arteries as affected by an acute increase of blood pressure

Changes in pial arteries diameter and the condition of blood flow "dead point" in arterial anastomoses were established using the brain window during an acute increase of mean arterial pressure (MAP) induced by intravenous injection of norepinephrine (NE) with microcineangiography and the analysis of films and frames on a montage table and TAS ("Leitz"). During an acute increase of MAP the movement of blood flow "dead point" in anastomoses and the expansion of plasma segments occurred much more frequently than in normotension. The stabilization of blood flow "dead point" was observed at high constant MAP. Pronounced dilation of both pial arteries and veins first occurred in anastomoses, then spread to arterial branches. It is assumed that high vulnerability of the brain vessels of the borderline zones is due to breakthrough in autoregulation of cerebral blood flow on its upper limit and depends on the repeatedly changing directions of the blood flow and its moving "dead point", as the peripheral resistance of arterial anastomoses-forming branches under these circumstances changes in an irregular manner.     

Skeletal muscle [(V)\dot]O2 \dot V_{O_2 } in rat and lemming: Effect of blood flow rate

Summary The rate of oxygen consumption ( ) by skeletal muscle was investigated in isolated perfused hindlimbs of laboratory rats and lemmings (Lemmus). In both species, increased in proportion to blood flow rate, even at flow rates 4–5 times above resting level. The slope of the line relating to skeletal muscle blood flow was significantly greater in the lemming than in the rat. This may be related to the inverse relationship between body weight and metabolic rate. These data support the hypothesis that in small animals a dependent relationship exists between blood flow and skeletal muscle .