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At least 865 records · Page 48Linked to original sources

PubMed1992

Functional implications of the pulmonary microcirculation. An update.

The microscopic anatomy of the pulmonary circulation was reviewed, comparing the evidence for two competing models, the sheet-and-post paradigm and the tubular paradigm. Implications of the two paradigms were analyzed for function, including flow, recruitment, distension, and diffusion. We conclude that the pulmonary microcirculation is not essentially different from the systemic microcirculation except that two layers of tubular capillaries are arranged on a central layer of connective tissue, the alveolar wall. We find no morphologic basis or theoretic advantage for the sheet-and-post concept.

Animals↗

PubMed1986

The local administration of relaxin induces changes in the microcirculation of the rat mesocaecum.

The clinical improvement of Raynaud's disease during pregnancy has been attributed to the increased relaxin (RLX) level in blood. Therefore we investigated the effect of topical porcine RLX (NIH-RXN-Pl) on the microcirculation of the mesocaecum of Wistar male rats, under direct microscope observation as judged by two observers. The hormone was applied locally to avoid systemic interferences either alone or after norepinephrine (NE) and promethazine (PM). The drugs were coded and the results were recorded independently by two observers. Porcine RLX induced rapid dilatation of the veins of the rat mesocaecum in a dose-related manner. The arteriolas and capillary flows were unchanged, while the venular flow was progressively reduced. The observed effects were sustained and disappeared with tissue wash-out. The RLX effects were reversed by addition of NE; conversely high doses of RLX were able to oppose the NE and PM vasospasm. We conclude that the local administration of RLX influences the microcirculation, possibly through an action on the smooth muscle of the venulae. The effects seems antagonistic with those of NE and PM.

Administration, Topical↗

PubMed1989

High and low doses of luteinizing hormone induce different changes in testicular microcirculation.

To study the effects of LH on total testicular blood flow and microcirculation, rats were treated with 2.5 or 25 micrograms LH sc and measurements were made on control rats and on LH-treated rats 1, 2, 3, 4, 6 and 12 h, after treatment. After treatment with 25 micrograms LH, total testicular blood flow, as measured with the radioactive microsphere method, was decreased at 6 h and increased at 12 h. Testicular microcirculatory blood flow was recorded with laser Doppler flowmetry and regular oscillations in blood flow, vasomotion, was observed in control rats. Vasomotion was not present 4 and 6 h after treatment with 25 micrograms LH, but returned at 12 h. Prior to and concomitantly with these changes in vasomotion, polymorphonuclear leukocytes accumulated in testicular microvessels and migrated into the interstitial tissue. These changes were followed, 6 h after treatment, by an increased vascular permeability, measured as increased testicular interstitial fluid volume. The lower dose of LH (2.5 micrograms), doubled plasma testosterone concentration and initially decreased interstitial fluid volume, and later induced a slight increase in blood vessel leukocytes. At the times studied, no changes could be observed in the other vascular parameters. In conclusion, it is suggested that LH, probably via some Leydig cell product, promotes regulatory effects on testicular microcirculation, but different magnitudes of LH stimulation induce different responses.

Animals↗

PubMed2006

Bioengineering assessment of acupuncture, part 2: monitoring of microcirculation.

In the second part of the review article, monitoring of microcirculation during acupuncture is described. Laser Doppler flowmetry and laser Doppler imaging provide easy-to-use, noninvasive, real-time measurements of local tissue blood flow. Using these types of biomedical equipment, it is possible to quantify and objectify peripheral changes in microcirculation during different methods of acupuncture stimulation (manual needle acupuncture and laserneedle acupuncture).

Acupuncture Therapy↗

PubMed1986

Relationship between human chorionic gonadotrophin-induced changes in testicular microcirculation and the formation of testicular interstitial fluid.

The relationship between testicular vascular permeability and testicular microcirculation as measured by laser Doppler flowmetry was studied in adult rats. In untreated control animals there was an oscillatory testicular blood-flow pattern with a frequency of 10.6 +/- 0.8 pulses/min and the amount of testicular interstitial fluid (IF) collected was 61.5 +/- 2.2 microliter/g testis. Treatment of the rats with 25-200 i.u. human chorionic gonadotrophin (hCG) s.c. 8 h before the experiment resulted in a change in the testicular flow pattern from pulsatile to continuous and an increase in IF volume. Treatment with hCG (50 i.u., s.c.) changed the testicular blood-flow pattern from oscillatory to continuous 4, 8 and 16 h after treatment. The flow pattern returned to being pulsatile 32 h after treatment with hCG. The IF information was increased at those times when the blood-flow pattern was continuous. No effects on blood flow or IF formation were observed with 12.5 i.u. hCG s.c. The present study shows a dose- and time-dependent covariation between the increase in testicular IF volume and the disappearance of the pulsatile flow in testicular microcirculation. It appears that a continuous flow pattern favours the transport of fluid from blood vessels to the interstitium.

Animals↗

PubMed1987

Effects of oestradiol-17 beta on testicular microcirculation in rats.

The effect of oestradiol-17 beta on testicular microcirculation in intact and hypophysectomized rats was studied before and after treatment with human chorionic gonadotrophin (hCG). Treatment of intact rats with oestradiol-17 beta for 5 days did not influence vasomotion but decreased testicular interstitial fluid volume (IFV). Treatment of intact rats with 50 IU hCG 8 h before the experiment began induced an increase in testicular IFV, abolished vasomotion and increased the accumulation of polymorphonuclear leucocytes in the testicular venules and interstitium. These changes were unaffected by pretreatment with oestradiol-17 beta, despite the decreased testosterone production. However, pretreatment with oestradiol-17 beta potentiated the hCG-induced migration of polymorphonuclear leucocytes to the interstitium. The interstitial fluid volume and number of polymorphonuclear leucocytes in blood vessels were decreased in hypophysectomized rats, and vasomotion was abolished. Daily treatment with 5 IU hCG increased the IFV and the number of polymorphonuclear leucocytes in blood vessels, and preserved vasomotion. Treatment of hypophysectomized rats with oestradiol-17 beta decreased testosterone production but did not influence basal IFV, vasomotion or the changes in IFV and vasomotion induced by 5 IU hCG. The present study shows that the regulation of testicular vascular permeability and vasomotion may not be directly related to testicular steroidogenesis, and that oestrogens are probably not involved as a mediator of the hCG-induced changes in testicular microcirculation.

Animals↗

PubMed1995

Effects of electrical stimulation of cervical sympathetic trunks on microcirculation in the facial nerve.

This study evaluates the circulatory effects of electrical stimulation of the cervical sympathetic trunks on blood flow in the common carotid artery and facial nerve tissue in dogs. Marked increases in arterial pressure and heart rate were observed due to electrical stimulation of the cervical sympathetic trunks, while blood flow volume in the common carotid artery and in the facial nerve tissue decreased markedly. It was assumed that microcirculation of the facial nerve is definitely impaired by electrical stimulation of the cervical sympathetic trunks, and the tonicity of the sympathetic nervous system appears to be a major factor in changes in the microcirculation of the facial nerve. It is well known that impaired circulation in the nutrient vessels of the facial nerve has an important effect on the pathogenesis of facial palsy. The hypertonicity of the sympathetic nervous system is closely involved in the onset of facial palsy.

Animals↗

PubMed2006

Bacterial translocation, microcirculation injury and sepsis.

Sepsis is the result from a complex bacterial-host interaction, which is an often-fatal response when host protective molecular mechanisms designed to fight invading bacteria surpass the beneficial intensity to the point of causing injury to the host. Increasing evidences have implicated the bacterial translocation (BT) as the main source for the induction of sepsis, although the beneficial effect of BT process has been related to the development of the intestinal immune response by physiological interaction between bacteria and host. In this article, we examined evolving concepts concerning to BT and discussed about its potential role in the promotion of microcirculation injury, moreover, its possible participation in the sepsis induction. According to our data obtained from in-vivo BT animal-model, both bacterial overgrowth and bacterial pathogenic determinants seem to be major predisposing factors for the induction of BT. Besides, translocation of luminal bacteria through the lymphatic via elicits the activation of the GALT inflammatory response contributing to microcirculation injuries, and the haematological via of BT was responsible to the systemic bacterial spread. On other hand, the combination of BT process to the pre-existing host systemic infection played a crucial role in the worsening of the clinical outcome. In our understanding, studies concerning to intestinal immune response and the pathophysiology of bacterial-host interaction, under normal and disease conditions, seems to be the key elements to the development of therapeutic approaches towards sepsis.

Animals↗

PubMedDate not supplied

Effect of glycerol on cochlea microcirculation.

Microcirculation in the cochlea of l2 normal anesthetized guinea pigs was investigated after intravenous infusion of 2.4 ml/kg of 40% glycerol. In these experiments endolymphatic PO2, blood pressure, cochlear microphonics, and endocochlear potentials were recorded. Administration of glycerol caused a significant increase in endocochlear PO2 for about 30 minutes. The improvement of hearing in patients with Meniere's disease is thus not only a result of the reduced hydrostatic pressure, as has been demonstrated by others, but may also be the result of vasodilatation, which improves microcirculation in the cochlea with resultant increases in endocochlear PO2.

Animals↗

PubMedDate not supplied

The laser Doppler flowmeter for measuring microcirculation in human nasal mucosa.

A new technique, based on the laser doppler principle, for measuring nasal mucosal microcirculation in humans, is presented. With this technique the relation between the blood flow and the temperature of the nasal mucosa was evaluated in healthy subjects exposed to peripheral cold stimulus. A decrease in blood flow and in mucosal temperature was found in all subjects when the feet were exposed to cold water for 5 min. The decrease in blood flow occurred almost momentarily and was restored to normal within the 5 min of exposure, while the drop in mucosal temperature was more gradual and persisted for a longer time. The implication of this study is that the laser doppler flowmeter seems to be a useful tool for estimation of changes in nasal mucosal microcirculation.

Adult↗

PubMed1993

Effects of carbogen on decreases in endocochlear potential and cochlear microcirculation induced by ischemia of the cochlea.

Preventive effects of carbogen on decreases in endocochlear potential (EP) and cochlear microcirculation induced by ischemia of the cochlea were examined in guinea pigs with intravital microscopy. The experimental model giving a severe decline in cochlear blood flow (CBF) was established by occlusion of both common carotid arteries and one of the vertebral arteries and i.v. infusion of adenosine triphosphate (ATP). The results showed no significant difference in the magnitude and pattern of the decrease in the cochlear microcirculation induced by ATP infusion and arterial occlusion before and after carbogen inhalation. However, even with a dramatic decrease in CBF, carbogen could reduce the decline in EP. The results clearly indicate that although carbogen fails to ameliorate cochlear ischemia in the face of a large impairment of the blood supply caused by a drop of blood pressure and cardiac output, it does in fact enhance the oxygen delivery to the cochlea and thus provide a therapeutic means of treating certain inner ear diseases caused by insufficient blood supply to the cochlea.

Animals↗

PubMed1995

A new fluorescent imaging procedure in vivo for evaluation of the retinal microcirculation in rats.

We investigated a new method for in vivo evaluation of the retinal microcirculation in rats using a cell-permeant fluorescent dye, acridine orange (AO), which stains cell nuclei and cytoplasm, and a scanning laser ophthalmoscope (SLO). AO, which binds and interacts with DNA and RNA, and thus stains cell nuclei and cytoplasm, was administered intravenously to rats. Fluorescein angiography was performed after administration of the AO, and fundus images were recorded on S-VHS videotape by means of an SLO. Argon laser was used as an exciter of the dye. The retinal vessels were stained with the dye, rendering the retinal microvasculature clearly visible. Cell nuclei and vessel walls were observed as greater fluorescence and lesser fluorescence, respectively. Leukocytes were also observed as highly fluorescent dots moving through the vessels. The results suggest that SLO visualization of AO uptake by cells may be a useful procedure for the evaluation of retinal microcirculation in vivo in rats.

Acridine Orange↗

PubMed1980

Acute effect of the carbon dioxide laser on the epicerebral microcirculation. Experimental study by fluorescein angiography.

The effect of laser radiation on the central nervous system has been studied in cases of clinical and experimental tumors. However, no report yet exists on the effects of laser radiation on the cerebral microcirculation in vivo. Cerebral fluorescein angiography permits observations of small vessels that are not possible by conventional angiography. In this study, disturbance in the epicerebral microcirculation after carbon dioxide laser radiation was localized. On fluorescein angiograms, a circular zone of nonfilling of fluorescein dye around the site of impact, 1 to 1.5 mm in diameter, was seen throughout from the arterial to later venous phase. Around the nonfilling area, thrombus formation in small vessles and extravasation of the dye were demonstrated. Such extravasation of the fluorescein remained after the dye had faded from the venules and veins. Microscopically, coagulation necrosis was observed to coincide with the area of nonfillin of fluorescein dye in the fluorescein angiograms. In areas surrounding this, edema, dilatation or rupture of the capillaries, and thrombus formation in the arterioles were observed. Such areas coincided with those of extravasation of the fluorescein dye.

Animals↗

PubMed1990

Perspectives of leukocyte activation in the microcirculation.

Recent evidence for a role of granulocytes in ischemic organ injury and in hemorrhagic shock is provided. Compared to red cell, granulocytes are large cells and have a stiff cytoplasm, making them prone to entrapment in the microcirculation. After activation, granulocytes become adhesive, they can elaborate superoxide radicals and release proteolytic enzymes. In the circulation a subgroup of granulocytes are in a spontaneously activated state. If during shock such cells become trapped in the microcirculation they impose a risk for organ injury. In a short term shock protocol, the group of surviving and non-surviving animals can be sharply distinguished by the number of activated granulocytes before shock. Experimental forms of granulocyte activation in the coronary circulation cause temporary trapping of cells, an increase in vascular resistance, and a transient reduction of muscle contraction even in the presence of a normal perfusion pressure. Detection of spontaneous granulocyte activation requires the development of new tests which can be carried out on fresh unseparated blood samples. We provide here also a critical evaluation of experimental neutropenia as a test for granulocyte related hypotheses.

Animals↗

PubMed2004

Changes of cytosolic [Ca2+]i in neutrophils in pancreatic microcirculation of rats with caerulein-induced acute pancreatitis under fluid shear stress.

AIM: To investigate the fluid shear stress induced changes of (Ca(2+))i in neutrophils in pancreatic microcirculation of experimental acute pancreatitis (AP). METHODS: Wistar rats (n = 36) were randomized into three groups. A model of AP was established by subcutaneous injection of caerulein. Low-shear 30 viscometer was used to provide steady fluid shear stress on separated neutrophils. The mean fluorescent intensity tested by flow cytometry was used as the indication of [Ca(2+)]i quantity. RESULTS: Under steady shear, cytosolic [Ca(2+)]i showed biphasic changes. The shear rate changed from low to high, [(Ca(2+)]i in different groups decreased slightly and then increased gradually to a high level (P<0.05). A close correlation was observed between the cytosolic [Ca(2+)]i level and the alteration of fluid shear stress in regional microcirculation of AP. CONCLUSION: The increase of [Ca(2+)]i is highly related to the activation of neutrophils, which contributes to neutrophil adhesion to endothelium in the early phase of AP. The effect of fluid shear stress on [Ca(2+)]i may play a crucial role in pancreatic microcirculatory failure of AP.

Acute Disease↗

PubMed2005

Effect of resveratrol on microcirculation disorder and lung injury following severe acute pancreatitis in rats.

AIM: To investigate the mechanism of resveratrol underlying the microcirculation disorder and lung injury following severe acute pancreatitis (SAP). METHODS: Twenty-four rats were divided into 3 groups (SAP, sham and resveratrol groups) randomly. SAP model was established by injecting 4% sodium taurocholate 1 mL/kg through puncturing pancreatic ducts. Sham (control) group (8 rats) was established by turning over the duodenum. Resveratrol was given at 0.1 mg/kg b.m. intraperitoneally. Rats were sacrificed 9 h after SAP was induced. Blood samples were obtained for hemorrheological examination. Lung tissues were used for pathological observation, and examination of microvascular permeability, dry/wet ratio and myeloperoxidase (MPO) activity. Gene expression of intercellular adhesion molecule-1 (ICAM-1) was detected by RT-PCR. RESULTS: Compared with SAP group, resveratrol relieved the edema and infiltration of leukocytes in the lungs. Resveratrol improved markers of hemorrheology: high VTB (5.77+/-1.18 mPas vs 9.49+/-1.34 mPas), low VTB (16.12+/-3.20 mPas vs 30.91+/-7.28 mPas), PV (4.69+/-1.68 mPas vs 8.00+/-1.34 mPas), BSR (1.25+/-0.42 mm/h vs 0.03+/-0.03 mm/h), VPC (54.67+/-3.08% vs 62.17+/-3.39%), fibrinogen (203.2+/-87.8 g/ L vs 51.3+/-19.1 g/L), original hemolysis (0.45+/-0.02 vs 0.49+/-0.02), and complete hemolysis (0.41+/-0.02 vs 0.43+/-0.02) (P<0.05). Resveratrol decreased the OD ratio of ICAM-1 gene (0.800+/-0.03 vs 1.188+/-0.10), dry/wet ratio (0.74+/-0.02 vs 0.77+/-0.03), microvascular permeability (0.079+/-0.006 vs 0.112+/-0.004) and MPO activity (4.42+/-0.32 vs 5.03+/-0.51) significantly (P<0.05). CONCLUSION: Resveratrol can improve the microcirculation disorder of the lung by decreasing leukocyte-endothelial interaction, reducing blood viscosity, improving the decrease of blood flow, and stabilizing erythrocytes in SAP rats. It may be a potential candidate to treat SAP and its severe complications (ALI).

Acute Disease↗

PubMed2005

Impact of antithrombin III on hepatic and intestinal microcirculation in experimental liver cirrhosis and bowel inflammation: an in vivo analysis.

AIM: To analyze the hepatic and intestinal microcirculation in an animal model of liver cirrhosis and inflammatory bowel disease (IBD) and to characterize the anti-inflammatory action of antithrombin III (ATIII) on leukocyte kinetics and liver damage. METHODS: Hepatic and intestinal microcirculation was investigated by intravital videomicroscopy. Standardized models of experimental chronic liver cirrhosis and bowel inflammation were employed. Animals were divided into four groups (n = 6/group): controls, animals with cirrhosis, animals with cirrhosis and IBD, animals with cirrhosis and IBD treated with ATIII. RESULTS: Cirrhosis facilitated leukocyte rolling and sticking in hepatic sinusoids (1.91+/-0.28 sticker/microm vs 0.5+/-0.5 sticker/microm in controls, P<0.05). The effect enhanced in animals with cirrhosis and IBD (5.4+/-1.65 sticker/microm), but reversed after ATIII application (3.97+/-1.04 sticker/microm, P<0.05). Mucosal blood flow showed no differences in cirrhotic animals and controls (5.3+/-0.31 nL/min vs 5.4+/-0.25 nL/min) and was attenuated in animals with cirrhosis and IBD significantly (3.49+/-0.6 nL/min). This effect was normalized in the treatment group (5.13+/-0.4 nL/min, P<0.05). Enzyme values rose during development of cirrhosis and bowel inflammation, and reduced after ATIII application (P<0.05). CONCLUSION: Liver cirrhosis in the presence of IBD leads to a significant reduction in mucosal blood flow and an increase in hepatic leukocyte adherence with consecutive liver injury, which can be prevented by administration of ATIII.

Animals↗

PubMed2006

Effect of shenfu injection on gastrointestinal microcirculation in rabbits after myocardial ischemia-reperfusion injury.

AIM: To investigate the effect of shenfu injection on gastrointestinal microcirculation after myocardial ischemic-reperfusion (IR) injury in rabbits and probe into the mechanism. METHODS: Forty healthy flap-eared white rabbits were randomly divided into 4 groups: IR injury control group (group I), shenfu injection 5 mL/kg per h group (group II), shenfu injection 10 mL/kg per h group (group III) and shenfu injection 20 mL/kg per h group (group IV). The four groups were treated with Lactated Ringer's solution, shenfu injection 5, 10, and 20 mL/ kg per h were infused intravenously 30 min before experiment respectively. The values of hemodynamics [mean arterial pressure (MAP), heart rate (HR), gastric intramucosal partial pressure of carbon dioxide (PCO2), blood gas analysis and pH] were measured and compared with those before myocardial ischemia, 60 min after myocardial ischemia and 60, 90, and 180 min after reperfusion. RESULTS: The MAP, HR and gastric intramucosal pH were (70.50 +/- 4.50) kPa, (165 +/- 14) beats per min, 7.032 +/- 0.024 in group I 60 min after myocardial ischemia, which were significantly decreased compared with those before myocardial ischemia (88.50 +/- 9.75 kPa, 217 +/- 18 beats per min, 7.112 +/- 0.035, P < 0.05). The MAP, HR and gastric intramucosal pH were significantly decreased in group I 60, 90, and 180 min after reperfusion (61.50 +/- 5.25 kPa, 133 +/- 31 beats per min, 6.997 +/- 0.025) compared with those before reperfusion respectively (P < 0.05), whereas the values were insignificantly different in groups II, III or IV after reperfusion, compared with those before reperfusion, and there were no significant differences between groups II, III, and IV after reperfusion. CONCLUSION: Pre-infusion of shenfu injection has a protective effect on gastrointestinal microcirculation after myocardial IR injury in rabbits, in a dose independent manner.

Animals↗