Gill blood flow control

The arrangement of the fish gill vasculature is quite complex, and varies between the different fish groups. The use of vascular casting techniques has greatly enhanced our knowledge of the anatomy of the branchial microcirculation, not least through the contributions of Pierre Laurent and co-workers at Strasbourg. At different physiological situations, the contact surface between water and blood (functional surface area) varies to balance oxygen uptake against osmotic water flow ("respiratory-osmoregulatory compromise"). This is controlled by nerves and by blood-borne or locally released substances that affect blood flow patterns in the gill. Histochemical techniques have been used to demonstrate neurotransmitter substances in the branchial innervation. In combination with physioly-osmoregulatory compromise" at different physiological situations.     

Effect of hypoxia on in vivo thromboxane and prostacyclin levels in arterial blood of rainbow trout, Oncorhynchus mykiss (Walbaum)

Endogenous levels of TXB₂ and 6-keto PGF_1a are reported in dorsal aortic blood from rainbow trout. Acute hypoxia induced an increase in TXB₂ levels whereas 6-keto PGF_1a was unaffected. We suggest that enhanced thromboxane synthesis might have a role in microcirculation of various organs in fish hypoxia.     

Comparative-biochemical analysis of lipids of blood serum lipoproteins of human and some animal species

Lipid composition of blood serum and total lipids of low density lipoproteins (LDL) and high density lipoproteins (HDL₂ and HDL₃) were studied in human (donors, patients with ischemic heart disease, bronchial asthma, chronic obstructive bronchitis, as well as with a combined pathology), in mammals predisposed to atherosclerosis (pig, rabbit) and resistant to atherosclerosis (rat, mink, Arctic fox), in birds (hen, pigeon), in teleost fish (white fish, pike-perch, pike, bream, burbot) and cartilaginous fish (sturgeon, housen). It has been established that the most enriched in lipids is the blood serum of animals, particularly of cartilaginous fish. Twice lower is the lipid content in blood serum of donors than of animals. However, in the vascular, bronchopulmonary, and combined human pathologies the lipid level rises statistically significantly. In human and in animals predisposed to atherosclerosis the main mass of lipid is located in LDL, whereas in animals resistant to this disease—in HDL. The ratio of the human lipid content in LDL/HDL increases from 1.4 (in donors) to 2.7 in pathological states—in ischemic heart disease and its combination with chronic obstructive disease. In animals, a decrease of this ratio is noted from 1.0 to 0.2 in cartilaginous fish. By the example of one taxon (fish) there is established a regularity that indicates that evolution of lipoproteins occurred with an increase of the lipid amount in the “younger” LDL and with a decrease of concentration of the “older” HDL.     

盐酸戊乙奎醚对大白兔耳微循环的影响

目的 通过观察盐酸戊乙奎醚(长托宁)注射液对清醒状态大白兔耳微循环的影响,对盐酸戊乙奎醚改善微循环的作用作初步探讨和研究.方法 用微循环观测仪观测用药前大白兔耳廓微循环血管管径、血流速度、血流量等进行综合评估出正常微循环血流指标作为对照,观察盐酸戊乙奎醚用药后对家兔耳微循环血流量变化,并用山莨菪碱作药效对照.结果 两组...     

The effects of slip velocity at a membrane surface on blood flow in the microcirculation

Closed-form solutions are presented for blood flow in the microcirculation by taking into account the influence of slip velocity at the membrane surface. In this study, the convective inertia force is neglected in comparison with that of blood viscosity on the basis of the smallness of the Reynolds number of the flow in microcirculation. The permeability property of the blood vessel is based on the well known Starling's hypothesis [11]. The effects of slip coefficient on the velocity and pressure fields are clearly depicted.     

Mass-transfer, utilization, and diffusion of oxygen in skeletal muscles of the stenohaline goby Gobius cobitus pallas under conditions of hypoosmotic medium

Effect of hypoosmotic conditions of medium on oxygen regime of skeletal muscles of the stenohalin goby Gobius cobitus Pallas was studied under conditions of experiment. The control fish group was maintained at 12–14‰, the experimental one—at 4.8–5.6‰. Duration of the experiment—44–45 days, water temperature—15 ± 1°C, photoperiod—12 day/12 night. It was established that under conditions of external hypoosmia there occurred hydration of the goby skeletal muscles and a decrease of their diffusion capability with respect to oxygen. The latter was accompanied by the tissue {ie215-1} decrease, which is indicated by low values of {ie215-2} in the venous blood outflowing from muscles. For the first 14–16 days of adaptation to the hypoosmotic medium there were restricted processes of mass transfer and oxygen utilization, which was associated with a decrease of the voluminous tissue blood flow and the blood oxygen concentration. These changes occurred on the background of the blood plasma hydration and a decrease of the number of circulated erythrocytes, and then they were completely compensated.     

蝮蛇抗栓酶对微循环作用的实验与临床研究

对实验性失血性休克的４０只大鼠和１５只家兔静注不同剂量的抗栓酶,用激光多普勒微循环血流计测定肾表面固定部位的微循环血流量,发现用药后血流量显著增加且与尿量相一致;阻断６０只沙鼠颈动脉造成脑缺血模型,在颅顶开窗用微循环显微镜观察用药后软脑膜微循环的变化,发现微循环血流速度加快并显示一定的冲击力,且能减少白细胞数及贴壁滚动;用２０只家兔做成ＤＩＣ模型,给抗栓酶后观察肠系膜微循环,发现毛细血管开放数增多,微循环流态改善。观察３３例脑血栓形成期病人用抗栓酶治疗前后甲襞微循环的变化,发现治疗后微循环总积分值改善,流态改善更明显     

The Effect of Cold Helium Plasma on Microcirculation in the Periwound Zone after Experimental Thermal Injury

Biophysics - Abstract—The effect of cold helium plasma on the state of microcirculation in the periwound zone after experimental thermal injury was evaluated. The experiments were performed...     

Changes in the blood microcirculation in the mouth mucosa in experimental stomatitis

Aphthous lesions in the oral mucosa (OM) were simulated in dog experiments by ligation of the common bile duct. In one of the experimental groups the beta-adrenoblocker propranolol was administered 30 min before surgery. Two hours after surgery the animals manifested changes in blood microcirculation of the OM. In animals treated with propranolol, the characteristics of blood microcirculation remained within normal. It is concluded that the development of aphthous lesions is preceded by functional disorders of blood microcirculation in the OM which are probably related to alterations in the neurovascular system.     

Éléments de physiologie et physiopathologie de la microcirculation et de rhéologie. Implications potentielles pour la circulation extracorporelle en chirurgie cardiaque de l’adulte

Cardiopulmonary bypass (CPB) is usually performed by defining therapeutic goals based on macro-hemodynamic parameters such as pump flow, mean arterial blood pressure, haemoglobin concentration or venous line saturation. Nevertheless, oxygen transport to tissues and cells is also dependent on the function of the microcirculation and the rheologic properties of blood. This articles summarizes for clinicians that perform CPB several aspects of physiology and pathophysiology of microcirculation and rheology. Physiological and pathophysiological changes of blood and plasma viscosities, red blood cell aggregation and deformability are explained. Potential clinical implications of changes of blood rheology are discussed.     

Study of endothelium-dependent blood oscillations in the human skin microcirculatory bed

Cutaneous microcirculation parameters were studied with laser Doppler flowmetry in healthy volunteers. To investigate endothelial-dependent peripheral blood flow oscillations the iontophoresis of 1% acetylcholine solution was carried out. To estimate the contribution of rhythmical components in blood flow signal the continuous wavelet-transform spectral analysis was used. To reveal correlation between microcirculation parameters under study the correlation analysis was used. The microcirculation index was shown to be the factor producing cross-correlation dependences. The only positive significant correlation between the blood flow oscillation amplitude in the range of endothelial activity normalized to mean microcirculation index at rest and maximal microcirculation index during the iontophoresis of acetylcholine was revealed.     

Active nitric oxide produced in the red cell under hypoxic conditions by deoxyhemoglobin-mediated nitrite reduction

Recent studies have generated a great deal of interest in a possible role for red blood cells in the transport of nitric oxide (NO) to the microcirculation and the vascular effect of this nitric oxide in facilitating the flow of blood through the microcirculation. Many questions have, however, been raised regarding such a mechanism. We have instead identified a completely new mechanism to explain the role of red cells in the delivery of NO to the microcirculation. This new mechanism results in the production of NO in the microcirculation where it is needed. Nitrite produced when NO reacts with oxygen in arterial blood is reutilized in the arterioles when the partial pressure of oxygen decreases and the deoxygenated hemoglobin formed reduces the nitrite regenerating NO. Nitrite reduction by hemoglobin results in a major fraction of the NO generated retained in the intermediate state where NO is bound to Hb(III) and in equilibrium with the nitrosonium cation bound to Hb(II). This pool of NO, unlike Hb(II)NO, is weakly bound and can be released from the heme. The instability of Hb(III)NO in oxygen and its displacement when flushed with argon requires that reliable determinations of red blood cell NO must be performed on freshly lysed samples without permitting the sample to be oxygenated. In fresh blood samples Hb(III)NO accounts for 75% of the red cell NO with appreciably higher values in venous blood than arterial blood. These findings confirm that nitrite reduction at reduced oxygen pressures is a major source for red cell NO. The formation and potential release from the red cell of this NO could have a major impact in regulating the flow of blood through the microcirculation.     

Effects of desensitization of capsaicin-sensitive afferent neurons on gastric microcirculation in rats depend on the blood glucocorticoid hormone level

The effects of desensitization of capsaicin-sensitive afferent neurons on gastric microcirculation were investigated before and after administration of indomethacin at ulcerogenic dose in adrenalectomized rats with or without corticosterone replacement and in sham-operated animals. We estimated the blood flow velocity in submucosal microvessels; the diameters and permeability of mucosal venous microvessels as parameters of gastric microcirculation. Desensitization of capsaicin-sensitive neurons was performed with capsaicin at the dose 100 mg/kg two weeks before the experiment. Adrenalectomy was created one week before experiment. In vivo microscopy technique for the direct visualization of gastric microcirculation and the analysis of the blood flow was employed. Indomethacin at ulcerogenic dose decreased the blood flow velocity in submucosal microvessels, caused dilatation of superficial mucosal microvessels and increased their permeability. Desensitization of capsaicin-sensitive afferent neurons potentiated indomethacin-induced microvascular disturbances in gastric submucosa-mucosa. These potentiated effects of the desensitization are obviously promoted by concomitant glucocorticoid deficiency. Thus, glucocorticoid hormones have a beneficial effect on gastric microcirculation in rats with desensitization of capsaicin-sensitive afferent neurons.     

Characteristics of fatty acid composition of <Emphasis Type="Italic">Gammarus lacustris</Emphasis> inhabiting lakes with and without fish

The effect of a biotic factor—the presence of predatory fish in water—on the composition and content of fatty acids in crustaceans was studied in the populations of the lake amphipod Gammarus lacustris from two lakes with fish and three lakes without fish. It was found that, at an overall increase in the quantity and quality of food resources (namely, increase in the content of eicosapentaenoic acid and docosahexaenoic acid (DHA) in the biomass), the relative rate of DHA accumulation in gammarids in the lakes without fish is higher than in the lake with fish.     

Manganese oxides as localized drivers of benthic invertebrate density and community structure

Hydrobiologia - Feeding upon the scales of other fish—lepidophagy—is a highly specialized foraging strategy in fish. Scale-eating is rare in teleosts, yet has evolved several times in...     

鲢、鳙肌肉生化成分的分析

同一季节收集的不同体长组的鲢、鳙肌肉的生化成分,随着鱼体的增长水分含量逐渐下降,而脂肪含量则逐渐增加,蛋白质、无氮浸出物及灰分变幅不大,且与体长变化无明显的从属关系;同一体长组的鳙肌肉水分高于鲢,而脂肪含量则低于鲢,蛋白质、灰分、无氮浸出物含量差异不大。同年收集的1+及2+龄鲢、鳙的肌肉生化成分随着季节的延续,水分含量逐步下降,蛋白质及脂肪含量逐步上升,无氮浸出物及灰分含量变化不大;1+龄鱼水分含量比2+龄鱼高,蛋白质及脂肪含量则比2+龄鱼低,其余成分含量差别不显著。       

Role of gastric microcirculation in the gastroprotection by glucocorticoids released during water-restraint stress in rats

Our previous investigations demonstrated that glucocorticoids released in response to stress protect gastric mucosa against stress-induced ulceration. This study was designed to determine whether gastric microcirculation is involved in the mechanism of gastroprotective glucocorticoid action. For this we evaluated the effects of deficiency of glucocorticoid production during 3 hr water-restraint stress and corticosterone replacement on the stress-induced gastric erosions, gastric microcirculation and arterial pressure in rats. The stress was produced in awake rats and gastric microcirculation and arterial pressure were evaluated in animals anesthetized in 3 hr after the onset of water-restraint stress. An in vivo microscopy technique for the direct visualization of gastric microcirculation was employed. The gastric submucosal and the superficial mucosal microvessels were monitored on television screen through a microscope and the pictures were stored by microfilming for the analysis of red blood cell velocity and vessel diameter. Gastric microcirculation was estimated on the base of both the volume blood flow velocity in submucosal microvessels and the diameter of superficial mucosal venous microvessels. Gastric erosions were quantitated by measuring the area of damage. Plasma corticosterone levels were also measured after 3 hr stress by fluorometry. Water-restraint stress induced an increase in corticosterone level, an appearance of gastric erosions, a decrease in volume blood flow velocity of submucosal microvessels, a dilatation of superficial mucosal microvessels, a decrease in arterial pressure. The deficiency of glucocorticoid production during water-restraint stress promoted the stress-induced gastric ulceration, a dilatation of mucosal microvessels, a decrease of blood flow velocity in submucosal microvessels and of arterial pressure. Corticosterone replacement eliminated the effects of deficiency of glucocorticoid production on all of the parameters under study. Thus, the stress-induced corticosterone rise decreased gastric ulceration, restricted both the reduction of blood flow velocity in submucosal microvessels and a dilatation of superficial mucosal venous microvessels during water-restraint stress. These data suggest that the gastroprotective action of glucocorticoids during stress may be provided by the maintenance of gastric blood flow.     

Nitric oxide influences red blood cell velocity independently of changes in the vascular tone

Nitric oxide (NO) plays a key role in regulation of vascular tone and blood flow. In the microcirculation blood flow is strongly dependent on red blood cells (RBC) deformability. In vitro NO increases RBC deformability. This study hypothesized that NO increases RBC velocity in vivo not only by regulating vascular tone, but also by modifying RBC deformability. The effects of NO on RBC velocity were analysed by intra-vital microscopy in the microcirculation of the chorioallantoic membrane (CAM) of the avian embryo at day 7 post-fertilization, when all vessels lack smooth muscle cells and vascular tone is not affected by NO. It was found that inhibition of enzymatic NO synthesis and NO scavenging decreased intracellular NO levels and avian RBC deformability in vitro. Injection of a NO synthase-inhibitor or a NO scavenger into the microcirculation of the CAM decreased capillary RBC velocity and deformation, while the diameter of the vessels remained constant. The results indicate that scavenging of NO and inhibition of NO synthesis decrease RBC velocity not only by regulating vascular tone but also by decreasing RBC deformability.     

Testicular blood flow and microcirculation in rats after treatment with ethane dimethyl sulfonate

The effects of ethane dimethyl sulfonate (EDS) on total testicular blood flow, microcirculation, and the testicular interstitial fluid volume (IFV) in rats were studied. In agreement with previous studies, treatment of control rats with human chorionic gonadotropin (hCG) induced an increase in IFV and total testicular blood flow as measured with radioactive microspheres. These effects of hCG were completely abolished in rats pretreated with EDS; in EDS-treated rats not receiving any hCG, there were decreases in IFV when compared with untreated control rats. Furthermore, the pulsatile pattern of testicular microcirculation registered with laser-Doppler flowmetry was abolished after EDS treatment, and this effect was not influenced by hCG treatment. The hCG-induced increase in IFV is associated with an increased accumulation of polymorphonuclear leukocytes locally in the testis, but this accumulation of leukocytes was not observed in rats pretreated with EDS. It was concluded from the present study that hCG-induced changes in total testicular blood flow and testicular microcirculation require functionally intact Leydig cells.     

Vagus nerve is involved in lack of blood reflow into sinusoids after rat hepatic ischemia

Although recovery of microcirculation is an important determinant for ischemia-reperfusion injury, little information is available about hepatic blood flow after ischemia. To examine regulatory mechanisms of postischemic hepatic microcirculation, we studied the sinusoidal blood flow after portal triad clamping of rat livers for 5, 15, or 30 min. Hepatic tissue blood flow and erythrocyte blood flow in sinusoids were measured using a laser-Doppler flowmeter and an intravital microspectroscope, respectively. There was a time of no blood flow (lag time) in sinusoids after declamping, dependent on the ischemic time. Cholinergic blockade agents eliminated the lag time, whereas nerve stimulation at the hiatus esophagus or on the hepatoduodenal ligament during reperfusion prolonged it. Chemical denervation with 10% phenol or surgical denervation on the hepatoduodenal ligament eliminated the lag time. The prolongation of lag time by nerve stimulation was completely abrogated by truncal vagotomy. These results suggest that the cholinergic vagus nerve is involved in causing the lag time of sinusoidal blood flow in hepatic ischemia-reperfusion.