Solubility of inert gases in dog blood and skeletal muscle

Solubility of H₂, Ar, CH₄ and SF₆ was determined at 310 K (37°C) in water, in saline (0.154 mol NaCl/l H₂O), in plasma and whole blood of dogs, and in homogenates of the dog gastrocnemius muscle. The liquids were equilibrated with pure gases, and the dissolved gases were extracted and measured by gas chromatography as described previously (Meyer, M.: Pflügers Arch. 375, 161–165, 1978). In saline, the solubilities were 4% (SF₆) to 15% (Ar) lower than in water. For dog blood the following mean values for the solubility coefficient (in mol · l^–1 · kPa^–1) were found: for H₂, 6.44; for Ar, 9.94; for CH₄, 11.44; for SF₆, 2.62. The red cell/plasma and the muscle/blood solubility ratios were near unity for H₂, Ar and CH₄ (ranging from 0.9 to 1.3); for SF₆, however, they were much higher (about 2.1), apparently due to the high solubility of SF₆ in hydrophobic substances (lipids).Supported by the Deutsche Forschungsgemeinschaft (SFB 89, Kardiologie Göttingen)     

Effects of diagnostic procedures during fiberoptic bronchoscopy on heart rate,blood pressure,and blood gases

Summary To investigate the effects of several endoscopic procedures like introduction of the bronchoscope, removal of the instrument, catheter suction, bronchoalveolar lavage and transbronchial biopsy on heart rate, systemic blood pressure, and transcutaneously measured blood gases 77 consecutive patients (age, 20–83 years) were studied. All patients received 10 l O₂/min via face mask during bronchoscopy. Sedation was performed with midazolam or diazepam. The different characteristics of each patient, e.g. age, sex, smoking habits, baseline values of heart rate and systemic blood pressure, underlying pulmonary disease and kind of premedication were examined separately to analyse their special effects on the course of bronchoscopy.During the fiberoptic bronchoscopy neither a slight decrease in transcutaneouspO₂ nor a small increase in transcutaneouspCO₂ led to a critical situation. Nevertheless it should be stressed that the time after removal of the instrument and finishing supplemental oxygen may be critical regarding hypoxia and hypercapnia especially in older patients with hypoxia being already present before starting the endoscopy. The hemodynamic indices did not change significantly. There was no difference between midazolam or diazepam concerning the parameters under study.If supplemental oxygen is given and adequate premedication is performed, monitoring of hemodynamics and blood gases during fiberoptic bronchoscopy is not necessary in patients without cardiovascular or respiratory risk.Abbreviations pO₂ partial pressure of oxygen in the arterial blood - pCO₂ partial pressure of carbon dioxide in the arterial blood - tcpO₂ transcutaneous partial pressure of oxygen - tcpCO₂ transcutaneous partial pressure of carbon dioxide - HR heart rate - p _syst systolic arterial pressure - p _diast diastolic arterial pressure - n number of values - S.E.M. standard error of the mean - p level of significance     

Blood gas analyses, ruminal and blood pH, urine and faecal pH in dairy cows during subacute ruminal acidosis

The aim of this study was to investigate the variations of some physiological parameters in dairy cows during subacute ruminal acidosis (SARA), a common important disorder of dairy cows that occurs in early lactation. pH changes in ruminal fluid collected by rumenocentesis were measured at ten farms stationed in different zones in the north of Italy. Additionally, the following parameters were measured: blood pH, faecal pH, urine pH, partial pressure of carbon dioxide oxygen, partial pressure of oxygen, bicarbonate level, base excess of extracellular fluid and oxygen content. Herds were divided into two groups according to their average ruminal pH: group A included farms with average ruminal pH > 5.8 (normal) and group B farms with average ruminal pH < 5.8 (acidosis). Unpaired Student’s t test was used to reveal statistical significances between the two groups. Ruminal pH changes due to pathogenesis can be diagnostic for SARA.     

Acute ethanol effects on blood pH,PCO2, and PO2 in LS and SS mice

The effects of ethanol on blood pH, PCO₂, and PO₂ were measured in LS and SS mice in an attempt to ascertain whether these lines of mice, which differ in CNS sensitivity to the behavioral effects of ethanol, also differ in sensitivity to physiological effects of this drug. Long-sleep (LS) female mice were injected intraperitoneally with 1.8, 2.5, 3.3, or 3.8 g/kg ethanol; short-sleep (SS) female mice were administered 2.5, 3.3, 4.1, or 4.7 g/kg. Blood pH, PCO₂, and PO₂ were assessed at 15, 30, 60, 120, or 180 min after injection of the 2.5 and 4.1 g/kg doses or at 60 min after injection of the 1.8, 2.5, 3.3, 3.8, 4.1, and 4.7 g/kg doses. Opposite effects on blood pH and PCO₂ over time were obtained in LS and SS mice at the 2.5 g/kg dose. Acidosis characterized the LS line, whereas alkalosis characterized the SS. The results obtained with SS mice at the 4.1 g/kg dose were similar to those obtained with LS mice at the 2.5 g/kg dose. The dose-response curve for the SS mice generated at 60 min post-injection lies to the right of that for the LS mice. The effects of high ethanol doses on SS mice resemble the effects of low doses on LS animals. Thus, the two lines of mice differ in response to the effects of ethanol on these parameters related to respiration. The difference in sensitivity to the respiratory depressant effects of ethanol may contribute to the differences in behavioral sensitivity between the two lines.     

Blood gases at several levels of oxygenation in rats with a left-shifted blood oxygen dissociation curve

Theoretical deductions have shown that a shift of the blood O₂ dissociation curve (ODC) to the right might improve O₂ transport to tissues at normoxia and at mild hypoxia whereas at severe hypoxia the organism should be better off with an ODC shifted to the left (Turek et al., 1973b; Turek and Kreuzer, 1976). The present study was performed in order to ascertain this ambiguous effect of an ODC shift depending on the degree of hypoxia in intact animals. A major displacement of the ODC to the left was achieved in rats by chronic administration of sodium cyanate (NaOCN). Control animals received sodium chloride (NaCl) instead. Arterial and mixed-venous , , and pH were measured at normoxia and during breathing 14.9, 8.0, or 5.6% O₂ in N₂ in both groups. From , pH, ODC and arterial hematocrit, arterial and mixed-venous O₂ contents were estimated and as an index of blood O₂ extraction was obtained. At normoxia and during breathing 14.9% O₂ the NaOCN rats had a lower mixed-venous than the NaCl rats without any difference in pH. Arterio-venous O₂ difference did not differ at normoxia but was lower in NaOCN rats at 14.9% O₂. However, at 8.0 and 5.6% O₂ the NaOCN rats had a higher mixed-venous , an increased , and a higher pH (arterial and mixed-venous). At 5.6% O₂ the NaCl rats developed a severe acidosis concomitant with pronounced hypocapnia. These findings confirm that rats with a left-shifted ODC have an impaired O₂ transport to tissues at normoxia and mild hypoxia but a more efficient O₂ transport at severe hypoxia as compared with rats with an unshifted ODC, in agreement with our previous theoretical studies.Preliminary communications of part of this material at the FASEB Meeting in Anaheim, California, on April 11–16, 1976 (Fed. Proc.35, 526, 1976), and at the Dutch Federation Meeting in Amsterdam on April 21–23, 1976 (Volume of Abstracts, p. 381)     

肠淋巴再灌注对肠系膜上动脉闭塞性休克多器官损伤的影响

目的：观察肠淋巴再灌注（MLR）对肠系膜上动脉闭塞性（SMAO）休克大鼠血压、存活率以及器官功能的影响。方法:Wistar雄性大鼠均分为4组：sham组，仅麻醉与手术；MLR组，夹闭肠系膜淋巴管（ML）1 h，再灌注2 h；SMAO组，夹闭肠系膜上动脉（SMA）1 h，再灌注2 h；MLR+SMAO：夹闭ML和SMA1 h，再灌注2 h。观察3 h期间平均动脉血压（MAP）变化后，观察肺、肝、肾、心肌功能和形态学变化。记录24 h存活率。结果:①sham、MLR、SMAO组大鼠24 h存活率（分别为100%、83.3%、66.7%）显著高于MLR+SMAO组（0%）。②夹闭SMA或ML前10 min，组间MAP无差异；SMAO组MAP在夹闭后多个时点显著高于MLR+SMAO和sham组；再灌注后，MLR和sham组MAP无明显变化，SMAO和MLR+SMAO组MAP迅速下降，后逐渐回升，SMAO组多个时点低于MLR和sham组，MLR+SMAO组在所有时点均低于MLR、sham和SMAO组。③MLR+SMAO组天门冬氨酸氨基转移酶（AST）、丙氨酸氨基转移酶（ALT）、尿素氮（BUN）、肌酐（Cre）、乳酸脱氢酶-1（LDH-1）、肌酸激酶同工酶（CK-MB）均显著高于sham组、MLR组、SMAO组，且SMAO组的这些指标显著高于sham组、MLR组。形态学观察显示sham组与MLR组的肺、肝、心、肾结构基本正常，SMAO组各脏器有一定的组织学损伤，而MLR+SMAO组则可见炎症、出血、核浓缩、破碎等严重病变。结论:MLR可加剧SMAO休克多个器官损伤，肠淋巴途径在SMAO休克的发病学中具有重要作用。     

Arterial blood gases,muscle fiber diameter and intercapillary distance in cardiac hypertrophy of rats with an old myocardial infarction

In rats with a myocardial infarction due to ligation of the left coronary artery a marked right ventricular hypertrophy developed after 41/2 weeks. At this time no difference against control animals was observed in arterial , , pH, ideal alveolar , and alveolar-arterial O₂ pressure difference, as measured in unanesthetized animals at normoxia. In histological sections of the heart stained by PAS reaction capillaries and muscle fibers were counted, and the mean intercapillary distance and muscle fiber diameter were estimated. In the right ventricle of the rats with myocardial infarction both increased when compared with control animals or with sham-operated rats. Fibercapillary ratio was the same in all three groups. Similar results were obtained in the remaining undamaged tissue of the left ventricle of rats with a myocardial infarction when compared with the left ventricle of control or sham-operated rats. Findings concerning intercapillary distance suggest that also in the myocardium which remains intact during the development of the infarction and later hypertrophies, tissue oxygen transport might be impaired, particularly during a stress situation. Results in the right ventricle of rats with myocardial infarction show an opposite trend against rats exposed chronically to simulated high altitude, where in the hypertrophied right ventricle a shorter intercapillary distance occurs and therefore an improvement of tissue oxygen transport might be expected.Dedicated to Professor Dr. Adolf Faller, University of Fribourg, Switzerland, on his 65th birthdayPresented in part at the IXth World Conference of the European Society for Microcirculation, Antwerp, July 5–9, 1976     

Aestivation in the South American lungfish, Lepidosiren paradoxa: effects on cardiovascular function, blood gases, osmolality and leptin levels

The African (Protopterus sp.) and South American lungfish (Lepidosiren paradoxa) inhabit shallow waters, that seasonally dry out, which induces aestivation and cocoon formation in Protopterus. Differently, L. paradoxa has no cocoon, and it aestivates in a simple burrow. In water PaCO(2) is 21.8+/-0.4mmHg (mean values+/-S.E.M.; n=5), whereas aestivation for 20 days increased PaCO(2) to as much as 37.6+/-2.1mmHg, which remained the same after 40 days (35.8+/-3.3mmHg). Concomitantly, the plasma [HCO(3)(-)]-values for animals in water were 22.5+/-0.5mM, which after 20 days increased to 40.2+/-2.3mM and after 40 days to 35.8+/-3.3mM. Initially in water, PaO(2) was 87.7+/-2.0mmHg, but 20 days in aestivation reduced the value to 80.5+/-2.2 and later (40 days) to 77.1+/-3.0mmHg. Meanwhile, aestivation had no effect on pHa and hematocrit. The blood pressures were equal for animals in the water or in the burrow (P(mean) approximately 30mmHg), and cardiac frequency (f(H)) fell from 31beats min(-1) to 22beats min(-1) during 40 days of aestivation. The osmolality (mOsmkgH(2)O(-1)) was elevated after 20 and 40 days of aestivation but declined upon return to water. The transition from activity to aestivation involves new set-points for the variables that determine the acid-base status and PaO(2) of the animals, along with a reduction of cardiac frequency.     

Differential effects of ethanol concentration on blood pH, PCO2 and PO2 in LS and SS mice

Concentration-dependent effects of ethanol upon behavior and upon physiological regulatory mechanisms have been suggested. In a previous study, we found that the concentration of an acute ethanol injection confounded dose-response relationships for measures of blood pH, PCO2, and PO2. Two lines of mice that differ in CNS sensitivity to the hypnotic effects of ethanol (long sleep, LS; short sleep, SS) have also been found to differ in sensitivity to the physiological depressant effects of this drug. Therefore, we designed the present study to examine how intraperitoneal (IP) injections of varying ethanol concentrations differentially affect blood parameters (pH, PCO2, and PO2) and respiration rate in the LS and SS mouse lines. Different groups of LS female mice were injected IP with 165.0, 198.8, 248.1, or 330.0 mg/ml ethanol at a constant dose of 3.3 g/kg. Groups of SS female mice received 205.0, 247.0, 308.3, or 410.0 mg/ml ethanol at a dose of 4.1 g/kg. Blood parameters and respiration rate were measured at 60 min post-injection. In both the LS and SS mice, increasing concentrations of ethanol caused a progressive decline in respiration rate and blood pH. Blood PCO2 values were greater than control only at the highest ethanol concentration. Concentration-dependent effects of ethanol on blood PO2 values were not found in either line. However, LS PO2 was significantly elevated from the control value at all ethanol concentrations. These results suggest that a dose-response relationship may be obtained by varying ethanol concentration for some physiological measures, but not for others. Thus, attention should be paid to differences in concentration as well as amount of ethanol when dose-response curves are to be constructed.     

A quantitative study of the relation between intracellular pH and force in rat mesenteric vascular smooth muscle

Strips of rat mesenteric artery were loaded with carboxy-seminaphthorhodafluor (SNARF) to measure intracellular pH (pH_i) and force simultaneously. pH_i was altered by using weak acids and bases. Alkalinization produced an increase in force. For equal elevations of pH_i a greater and faster increase of force was obtained in depolarized (high K⁺) than in non-depolarised preparations. Acidification produced little change in force unless the tissue was contracted (high-K⁺), in which case it elicited relaxation. Examination of the relationship between pH_i and force in depolarized preparations showed that acidification produced a greater change in force than alkalinization. Removal of weak bases produced a transient acidification that was accompanied by a fall in force in all preparations. This was followed by a secondary contraction in depolarized preparations during the period over which pH_i was acidic and being restored to resting values. Some preparations demonstrated a hysteresis in the relation between pH_i and force. It is concluded that the relationship between pH_i and force in mesenteric vascular smooth muscle is not constant but depends on the previous history of the preparation, and may involve differences in the interactions between H⁺, Ca²⁺ and the contractile machinery.     

Effect of hemodilution and hemoconcentration on postischemic alterations of microvessels in rabbit paired auricles

Morphometric parameters of microvessels in paired rabbit ears and blood sampled from the internal vein were studied after ischemia reproduced under conditions of prior hemodilution and hemoconcentration. In hemodilution the postischemic alterations were found to be more pronounced in microvessels of the left ear, while for the right the same was true for rheological characteristics of the outflowing blood. Under conditions of hemoconcentration after ischemia the changes in rheological indexes were more marked on the left and in vasomotor indexes on the right. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 3, pp. 352–354, March, 1996 Presented by V. V. Kupriyanov, Member of the Russian Academy of Medical Sciences     

The in vivo relationship between blood flow, contractions, pH and metabolites in the rat uterus

 Little is known about the relationship between smooth muscle contractile activity and its blood supply. We have therefore investigated this in the rat uterus, using laser-Doppler flow measurement and intra-uterine pressure recordings. We found an inverse linear relationship between flow and contractile activity. There was no evidence for a critical level of flow, above which function is maintained and below which it declines; even small reductions in blood flow decreased uterine force. Force was rapidly restored upon reperfusion. Reactive hyperaemia was absent from all but 6 of the 41 preparations studied. We used ³¹P nuclear magnetic resonance (NMR) spectroscopy to measure concentrations of adenosine triphosphate (ATP), phosphocreatine (PCr), inorganic phosphate (Pi) and intracellular pH (pH_i) simultaneously with force and flow. Reductions in flow were associated with significant reductions in [ATP], [PCr] and pH_i, and an increase in [Pi]. These changes were related to flow significantly and linearly and their effects on force may be additive. These data show that uterine smooth muscle is closely dependent upon its blood supply for maintaining both normal force production and metabolite levels. Consequently, even small decrements in flow may have deleterious functional effects. Received: 17 July 1997 / Received after revision: 1 November 1997 / Accepted: 26 November 1997     

Reporting of delayed adverse donor reactions in whole blood donors: Just the tip of an iceberg!

Background and objectivesThe study was planned to determine the incidence and analyze how various epidemiological factors tend to be associated with delayed adverse donor reactions (ADR).Material and methodsThe prospective observational study was conducted in Department of Transfusion Medicine of tertiary care hospital from January to December 2019. Eligible blood donors were observed for any adverse reactions after 15 minutes of removal of phlebotomy needle. Further, telephonic calls were made to each enrolled blood donor on day-2 and day-7 of the whole blood donation. For each day, two calls were made at an interval of 4 hours before declaring the participant to be non-responder.ResultsA total of 1540 (84.1%) blood donors responded on day-2 and 1610 (87.9%) responded on day-7 of follow-up. Total 180 (11.2%) blood donors experienced delayed ADRs. Two donors (1.1%) experienced on-site while 178 (98.89%) reported off-site delayed ADRs when followed-up telephonically. The commonest delayed ADRs reported were bruise (n = 72; 30.9%), arm-pain (n = 61; 26.2%) and generalised weakness (n = 44; 18.9%). Female donors (27.3% vs. 11.2%; P = 0.004), first time donors (15.2 vs. 9.9%; P = 0.002), donors with low body-weight (range of 45–60 kg; 15.9% vs. 11.5% vs. 6.1%; P = 0.011) and body mass index < 18.5 (24% vs. 12.5% vs. 9.7% vs. 11.3%; P = 0.028) experienced more delayed ADRs.ConclusionBlood donors do experience delayed ADRs but these are not reported to the blood centers as these are usually mild. However, it is important to capture these delayed adverse donor reactions and report it to National Hemovigilance Program so that strategies can be formulated to prevent their occurrence and recurrence.     

Changes in blood flow in conduit artery and veins of the upper arm during leg exercise in humans

This study investigated changes in blood flow in the conduit artery, superficial vein, and deep vein of the upper arm during increase in internal temperature due to leg cycling. Additionally, we sought to demonstrate the contributions of blood velocity and vessel diameter on blood flow responses. Fourteen subjects performed supine cycling exercise at 60–69% maximal oxygen uptake for 30 min at an ambient temperature of 28°C and relative humidity of 50%. Blood velocity and diameter in the brachial artery, basilic vein (superficial vein), and brachial vein (deep vein) were measured using ultrasound Doppler, and blood flow was calculated. Blood flow in the artery and superficial vein increased linearly with rising oesophageal temperature (ΔT _oes) after ΔT _oes was about 0.3°C (within threshold), as well as cutaneous vascular conductance on the forearm. Changes in blood velocity in these vessels were similar to those in blood flow. Conversely, the brachial artery and superficial vein diameter did not affect the blood flow response. Blood flow variables in the deep vein did not change remarkably with rising ΔT _oes. These results suggest that blood flow response, by an increase in velocity, in the conduit artery with rising ΔT _oes during exercise is similar to that in the superficial vein, but not deep vein. Also, it is indicated that these increases in blood flow relate to the increase in skin blood flow on the forearm with the rise in body temperature during exercise.     

血压对大鼠脑缺血/再灌注损伤的影响

目的： 研究血压变化对大鼠脑缺血/再灌注模型的影响。方法: 44只SD大鼠随机分为低血压组、正常血压组、高血压组及尿激酶/高血压组,制作缺血2 h再灌注24 h脑缺血/再灌注损伤模型,再灌注起始分别应用降压药物或升压药物改变平均动脉压水平（约20 mmHg）持续1 h,观察其神经功能改善、梗死体积、出血性转化的发生。结果: 再灌注24 h,低血压组神经功能恶化,其它各组均有不同程度的恢复;随着血压的升高,大鼠脑梗死体积有逐渐减小的趋势;尿激酶/高血压组出血性转化发生率最高,其次为低血压组及高血压组,而正常血压组最低;尿激酶/高血压组梗死灶周围皮层区MMP-9阳性细胞计数与其它各组比较均有显著差异（P<0.05）。结论: 再灌注期间升高血压有利于脑缺血大鼠神经功能预后的改善。大鼠脑缺血再灌注模型出血性转化发生率随着血压的升高或降低均有增加的趋势,其发生可能与MMP-9的过量表达有关。     

Influence of changes in the acid-base composition of the ventricular system on cerebral blood flow in cats

Summary In ventriculo-cisternal perfusion experiments performed in mechanically ventilated cats maintained under nitrous oxide anesthesia, the bicarbonate concentration of the ventricular perfusion fluid was decreased (from 21 to 4 mmol/l) or increased (from 21 to 84 mmol/l) during time intervals ranging from 45 to 120 min. The blood flow was measured in the caudate nucleus with two different methods: in a first series of experiments the temperature difference was continuously measured between a heated thermojunction and a reference junction, both devices being placed symmetrically in the right and left caudate nucleus (heat clearance method), while in a second series of experiments, the local blood flow was estimated from the rate of clearance of¹³³Xenon injected in micro-amounts (8–10 l) into the caudate nucleus. A decrease in the bicarbonate concentration of the ventricular perfusion fluid increased the blood flow in the caudate nucleus, estimated by both methods, while an increase in the bicarbonate concentration produced the opposite effect. The same alterations in the bicarbonate concentration of the ventricular perfusion fluid produced no detectable change in the hemispheric cerebral blood flow, measured by the clearance of¹³³Xenon injected into the carotid system.Finally, the bicarbonate concentration was independently altered in one of the lateral ventricles during bilateral ventricular perfusions, and changes in the blood flow distribution were studied in the caudate nuclei with a particle distribution method (⁸⁵Sr or¹⁴¹Ce labeled carbonized microspheres injected into the left heart ventricle). A ventricular perfusion, asymmetric with respect to the bicarbonate concentration induced an uneven distribution of the microspheres and hence of the local blood flow between both caudate nuclei. The results of the present experiments clearly argue in favour of a local influence of tissue pH on the blood flow in paraventricular gray matter.An abstract of this work was presented at the International Symposium on cerebral blood flow regulation, acid-base and energy metabolism in acute brain injuries held in Rome-Sienna, October 1971.     

The value of potassium,pH and D-dimer levels in early diagnosis of acute mesenteric ischemia: an experimental study on rats

IntroductionThe aim of this randomized controlled experimental study was to evaluate the efficacy of potassium, pH and D-dimer levels in blood, as well as potassium and pH levels in peritoneal lavage fluid, in the early diagnosis of acute mesenteric ischemia.Material and methodsThis study was conducted at the Istanbul University Center of Experimental Medicine after having received approval from the Istanbul University animal testing ethics committee. Male albino Wistar rats (n = 24; 250 to 350 g) were divided into two control groups and two ischemic groups. Levels of potassium, pH, and D-dimer in blood and levels of potassium and pH in peritoneal lavage fluid were analyzed for 1 h and 2 h after the induced acute mesenteric ischemia procedure. The degree of ischemic injury was determined using the histopathological damage score in tissue samples taken from the terminal ileum.ResultsIschemic groups had statistically significant differences in potassium and pH in blood and peritoneal lavage fluid compared to non-ischemic groups (p < 0.05). There was no significant difference between control and ischemic groups in terms of D-dimer and histologic grading results after 1 h (p = 0.132, p = 0.475 respectively), while there was a significant difference between control and ischemic groups after 2 h (p < 0.05).ConclusionsThe levels of potassium, pH, and D-dimer could be useful in daily practice for the early diagnosis of acute mesenteric ischemia.     

Distribution of oxygen tension on the surface of arterioles, capillaries and venules of brain cortex and in tissue in normoxia: an experimental study on rats

 The distribution of oxygen tension (PO₂) was studied in normoxia on the surface of arterioles, capillaries and venules of rat brain cortex, both longitudinally and in tissue radially from the wall of microvessels. Along the arteriolar tree, PO₂ decreased from 81.2±6.2 mmHg (mean±SD) on 1°A (first-order branch) arterioles to 61.5±12 mmHg on 5°A arterioles. Transmural flux of oxygen from blood to tissue increased markedly at the level of minute 4°A–5°A arterioles. At the arterial end of cortical capillaries, PO₂ averaged 57.9±10.6 mmHg, n=19, (or, in terms of blood oxygen saturation SO_2; 82±9%) and 258±19 μm downstream 40.9±11.5 mmHg, n=19, (SO₂ 59±18%). The averaged PO₂ drop on the capillaries studied was 17±9 mmHg, and the longitudinal PO₂ gradient was accordingly 0.07±0.04 mmHg/μm (SO₂ 0.1±0.06%/μm). The radial profiles of tissue PO₂ recorded near arterioles, capillaries and venules clearly demonstrated that all these microvessels supply oxygen to brain tissue. The PO₂ distribution on venules was characterized by pronounced heterogeneity. Received: 30 March 1998 / Received after revision: 28 July 1998 / Accepted: 25 November 1998     

微血管内红细胞的流速及白细胞对血流的调节作用

血流速度的测量是微循环研究最主要的参数之一。本实验采用30-1000幅/秒超高速显微摄像录像技术,记录及测量了正常大鼠肠系膜微循环申细动脉、毛细血管、细静脉的血流速度。8只大鼠微血管的内径从4μm—40μm的血管120根,细动脉直径最大25μm,血流速度平均5.86±0.76mm/秒。随着血管直径的减小,血流速度明显减慢,在4—6μm的毛细血管内红细胞的流速平均2.29±0.9mm/秒。在40μm直径的细静脉血流平均2.8±0.8mm/秒,比毛细血管的流速快。白细胞在微血管内流动时其流速和红细胞相同,白细胞贴附在血管壁上滚动时。速度从0.16-0.74mm/秒。白细胞贴壁不再滚动时,有的会穿过血管壁而游走到血管周围的组织,白细胞贴壁数量增多时,可使管腔变小。     

Changes in blood flow in a conduit artery and superficial vein of the upper arm during passive heating in humans

The purposes of this study were (1) to evaluate changes in blood flow in the brachial artery and basilic vein of the upper arm with a rise in internal temperature during passive heating; and (2) to investigate the contributions of blood velocity and anteroposterior vessel diameter to these blood flow changes. Ten subjects rested in the supine position between a pair of tube-lined sheets. Thermoneutral water was circulated through the tubes to keep a mean skin temperature of 34–35°C, and then hot water was circulated to maintain of 37–38°C. The blood velocity and diameter in the brachial artery and basilic vein were continuously monitored by Doppler ultrasound technique and used to calculate blood flow. Blood flow in the brachial artery and basilic vein increased linearly as the oral temperature (T _or) rose by ≤0.6°C. The magnitude of the change in blood flow did not differ significantly between the two vessels. In addition, plots of ΔT _or versus blood flow yielded slopes that did not differ significantly between the brachial artery and the basilic vein. As T _or increased, blood velocity, but not diameter, also increased. In conclusion, blood flow in the brachial artery and the basilic vein increased linearly as the internal temperature variable T _or increased ≤0.6°C. In both vessels, the passive heating-induced increases in blood flow resulted primarily from a change in blood velocity, rather than from a change in diameter.