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Results for “Microcirculation”

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At least 145 records · Page 8Linked to original sources

PubMed1989

A comparison of the effects of photodynamic therapy on normal and tumor blood vessels in the rat microcirculation.

The effects of light activation of the tumor photosensitizer dihematoporphyrin ether (DHE) were studied in the microcirculation of the rat cremaster muscle. Arterioles and venules in an implanted chondrosarcoma were studied by in vivo television microscopy and were compared to normal vessels of the same size elsewhere in the preparation and in control preparations. Activation with green light (530-560 nm, 200 mW/cm2, 120 J/cm2) 48 h after intraperitoneal injection of DHE (10 mg/kg body wt) resulted in significant narrowing of diameters of red blood cell columns in tumor arterioles and venules. The response in normal and control arterioles and venules was not significantly different from that seen in the tumor vessels except that the control arterioles did not remain significantly constricted during the treatment period. Treatment resulted in stasis of blood flow in 90% of tumor and normal arterioles at the completion of light activation. In venules, stasis of blood flow was observed in 75% of tumor and 70% of normal vessels. Vasoconstriction was the primary response in arterioles, while thrombosis predominated in venules. Morphologic assessment of light-activated vessels in the cremaster preparation by transmission electron microscopy revealed platelet aggregation with damage to endothelial cells and smooth muscle cells. Perivascular effects observed included interstitial edema and damage to skeletal muscle cells. In the tumor-bearing preparation, no direct cytotoxic effect on the tumor cells was shown. The surrounding vessels exhibited similar vascular stasis, but the lining cells appeared minimally affected. Photoactivation of DHE results in significant changes in the microcirculation which lead to stasis of blood flow. In this model, the response was similar for the normal microvasculature and for the microcirculation of an implanted chondrosarcoma. These effects may account, in part, for the mechanism of action of photodynamic therapy.

Animals↗

PubMed1988

New aspects of the theory of microcirculation.

New aspects and details of the mechanism of the microcirculation in the tissues are discussed in the paper. Particular attention is payed to the role of the blood pressure amplitude for the filtration and resorption processes through the capillary wall. A new model of the microcirculation is discribed in which the interstitial space is considered as a functional unit determining the intensity of the transcapillary exchange processes. The components of the hydraulic interstitial pressure are characterized as well as the process of formation and transport of limphatic fluid. The proposed model is a base for the better understanding of the theory of microcirculation.

Humans↗

PubMed1988

[Renal microcirculation in experimental acute pancreatitis of dogs--the effect of pancreatic protease inhibitor and dopamine].

To understand the renal microcirculation in acute pancreatitis is important to know the pathophysiology of renal insufficiency frequently observed as one of multiple organ failures in severe acute pancreatitis. In mongrel dogs acute pancreatitis was experimentally introduced by autologous bile added trypsin injection into the pancreatic duct. The effect of new synthesized pancreatic protease inhibitor (PATM) and dopamine in a dose of 3mg/kg/hr and 10 micrograms/kg/min were investigated, respectively. In acute pancreatitis dogs, renal arterial blood flow and renal tissue blood flow immediately fell and gradually decreased in time course of experiment and renal vascular resistance increased from 2 hours after onset of pancreatitis. When pancreatic protease inhibitor (PATM) was infused in acute pancreatitis dogs, blood pressure and pulse pressure relatively preserved during the experiment. Renal blood flow and renal tissue blood flow were maintained during the first 1 hour and thereafter slightly decreased, however which was less than that of no PATM treated dogs. When dopamine was infused in acute pancreatitis dogs, blood pressure was maintained during the first 90 minutes thereafter remarkably decreased. Renal blood flow was maintained within 60 minutes, however it remarkably decreased at the end of the experiment. This study suggested that renal microcirculation was disturbed from early period of acute pancreatitis in dogs and pancreatic protease inhibitor (PATM) had a beneficial effect of maintain the renal microcirculation.

Acute Disease↗

PubMed1988

[Disorders of microcirculation in subarachnoid hemorrhage and intracerebral hemorrhage].

The pathophysiological notions of hemodilution treatment of ischemic seizures with plasma expanders indicates the significance of microcirculation. Microcirculation disorders arise from the interrelations of hemodynamic, vascular, and hemorrheologic factors. It seems that hemodilution with hydroxyethyl starch reduces peripheral microcirculation disorders, thus inhibiting the development of cerebral edema. In the case of subarachnoid hemorrhage, the hemorrheologic factors deteriorate less severely when given antifibrinolytic treatment with Aprotinin. Simultaneous hemodilution with hydroxyethyl starch can counterbalance the already existing changes.

Blood Coagulation Tests↗

PubMed1987

[Intraoperative contact biomicroscopy as a method of assessing disorders of microcirculation in ileus of the small intestine].

The article describes an experience with visual microscopic assessment of disturbances of microcirculation in the small intestine in various forms of acute ileus. The assessment of microcirculation in the small intestine wall with the help of a microscope facilitates more objective establishment of indications for the resection of ischemic portions and drainage of the intestine by intubation. This method of direct assessment of microcirculation disturbances in the intestine is a promising one and requires further development.

Adult↗

PubMed1986

Effects of endotoxin on the splenic microcirculation and its cellularity.

This report describes the effects of endotoxin treatment on the intrasplenic microcirculation and cellularity in rats. Four and 16 h after a single intravenous injection of endotoxin (2 mg/100g body weight), altered intrasplenic microcirculation was observed. The open circulation was reduced from 97% in the control rats to 79% in the endotoxin treated rats, while the closed circulation increased from 3% in the controls to 21% in the endotoxin treated rats. Such changes in the splenic microcirculation may be partly due to the presence of fibrin and the pooling of polymorphonuclear leukocytes and red blood cells in the red pulp. The most apparent cellular changes seen in the white pulp of endotoxin treated rats 16 h after endotoxin injection are the disappearance of lymphocytes from the periarterial lymphatic sheath and the appearance of many giant macrophages within the white pulp. The giant macrophages contain lymphocytes undergoing various stages of degradation. This suggests that the lymphocytes may be injured by endotoxin treatment and are subsequently phagocytosed by macrophages.

Animals↗

PubMed1986

Effect of theophylline treatment on the functional hyperaemic and hypoxic responses of cerebrocortical microcirculation.

The purpose of the present study was to elucidate the importance of extracellular adenosine (ADO) in the regulation of cerebrocortical microcirculation during rest, hypoxia, and brain activation. Cerebrocortical microcirculation and fluorescence of reduced nicotinamide adenine dinucleotide (NADH) were measured by surface fluororeflectometry through a cranial window. Arterial hypoxia and brain activation were produced by respirating the animals with a gas mixture containing 6-7% O2 and by injecting 4-6 mg/kg metrazol into the lingual artery, respectively. These reactions were used as test before and after theophylline (THEO) treatment. In some of the experiments only the cortical area beneath the cranial window was treated with THEO (10(-4) M), in others 2 X 10(-4) mol/kg THEO was injected intraperitoneally. Potency of THEO in antagonizing the cerebral blood flow (CBF) increasing effect of topically applied ADO was also tested. It was found that superfusion of the brain cortex with artificial cerebrospinal fluid (mock CSF) containing 10(-4) M THEO does not alter resting CBF, but inhibits the CBF increasing effect of 10(-6) M and 10(-5) M ADO by approximately 70% and 40%, respectively. Intraperitoneally injected THEO increased CBF by approximately 60%, which has been attributed mostly to its action on the systemic circulation. Under control conditions, arterial hypoxia and epileptic seizures increased CBF by approximately 150% and 300%, respectively. Since neither topical nor systemic THEO treatment altered the vasodilatory and CBF increasing potency of arterial hypoxia and attenuated these effects of epilepsy slightly, it was concluded that extracellular ADO is not a critical factor in the regulation of cerebrocortical microcirculation.

Adenosine↗

PubMed1985

[Functional relations between microcirculation and oxygen supply (physiologic peculiarities in polarographic pO2 measurement in tissue)].

The measurement of the partial pressure of oxygen in the tissue is a method increasingly used in experiment and clinic, the technical prerequisites for this having been created by means of the development of polarographic measuring techniques (surface or scarifier-electrodes). The pO2-measurement of the tissue renders possible independent conclusions to the relations of microcirculation of the organs examined and to the effectiveness of the blood supply of the tissue as well as its homogeneity and nutritive achievement for the cellular metabolism. On the basis of the intravital microscopic findings in connection with perivascular pO2-measurement the pathophysiological peculiarities of this measuring method are discussed. The physiologically involved temporary and spatial inhomogeneities of the peripheral blood supply limit, however, the generalization of locally (approximately 200-300 microns3 measuring area) established oxygen values for diagnostics and therapy control. For the measurement an intact microcirculation and the simultaneous registration in several measuring places is necessary. Then the following informations may be obtained, e.g.: control of the exact dosage of an inspiratory O2-supply--control of the volume balance--control of the haemodynamic effect of drugs on the microcirculation.

Capillaries↗

PubMed1985

[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.

Animals↗

PubMed1979

[State of microcirculation in various zones of the heart in myocardial infarct complicated by congestive circulatory insufficiency].

A definite correlative connection has been revealed between the clinical course of myocardial infarction, the extent of affection of the heart muscle, the severity of the atherosclerotic process in the coronary arteries, and the condition of microcirculation in different zones of the heart. The severest affections of the heart muscle, stenosing coronarosclerosis and disorders of microcirculation in different zones of the heart were encountered in patients with myocardial infarction marked by a recurrent course and complicated by cardiogenic shock or congestive circulatory insufficiency. It is shown that the character of changes in microcirculation determines to a great measure the later condition of the structure and function of the myocardial muscle cell in areas near and remote from the infarction.

Adult↗

PubMedDate not supplied

The role of the coronary microcirculation in myocardial recovery from ischemia.

The aim of thrombolysis, angioplasty, and coronary artery bypass surgery is to "reperfuse" ischemic myocardium; however, reperfusion can cause further cardiac damage and compromise the coronary microcirculation. Because nutrient supply and exchange and delivery of pharmacologic agents require a patent microvasculature, the coronary microcirculation plays a major role in myocardial recovery from ischemia. It is known that ischemia-reperfusion can cause an increase in coronary permeability and microvascular plugging (No-reflow). The permeability to macromolecules is increased more than the permeability to smaller molecules. The permeability increase leads to extravasation of plasma proteins and a permeability edema. Furthermore, proteins that normally remain extravascular are now free to wash out the heart. Both microvascular effects, increased coronary permeability and No-reflow, compromise cardiac function. The degree of damage depends on the nature (No-flow versus low-flow) and length of ischemia. Unfortunately, both the increase in coronary permeability and the reduction in perfused capillarity advance with time during early reperfusion. Although the increase in permeability does not require the presence of platelets or leukocytes, it is apparent that the No-reflow response does. Mechanisms that may explain the microvascular responses to ischemia include cell swelling, damage caused by oxygen free radicals, and inflammatory responses that may or may not involve granulocytes. The permeability response may involve a calcium-mediated endothelial contraction because the macromolecular leakage that follows ischemia can be prevented by pretreating hearts with the calcium blocker nisoldipine. Protection of the coronary microcirculation should be included in any attempt to improve treatment of occlusive coronary artery disease.

Animals↗

PubMed1984

[Experimental study of the effect of portal vein occlusion on the mesenteric microcirculation].

The effect of portal vein occlusion (PVO) on the mesenteric microcirculation was studied with light microscope and electronmicroscope in the following three groups of mongrel dogs; the first group consisted of 3 dogs with laparotomy only, the second consisted of 10 dogs with PVO and the third consisted of 10 dogs with PVO and porto-femoral vein bypass using the antithrombogenic catheter (Anthron bypass tube). In the second group, dilatation of venula and slow blood flow in venula, patent A-V shunt and stasis in the capillary network were seen after 15 minutes. Hemorrhage and stasis in venula were observed after 15-30 minutes. Sludging and stasis in arteriole were also observed after 45-60 minutes. The hemorrhage of venula was progressive. Electronmicroscopically the vascular endothelial cell began to show abnormality after 15-30 minutes, and the microvilli of small intestinal mucosa showed pathological changes after 30 minutes. In the third group, the disturbance of the mesenteric microcirculation was mild even 4 hours after PVO. Both vascular endothelial cell and microbilli of the small intestinal mucosa were not damaged. We concluded that PVO causes the pathological changes of mesenteric microcirculation and intestinal mucosa at an early stage and the porto-femoral vein bypass using the antithrombogenic catheter is a safe and useful procedure when PVO is needed.

Animals↗

PubMedDate not supplied

[Characteristics of microcirculation in patients with diabetic angiopathies].

The radionuclide technique was used to study regional microcirculation in 139 patients with diabetic angiopathies of the lower limbs. All the examined demonstrated impairment of the muscular bloodflow, that increased depending on the disease stage and diabetes mellitus standing. No differences were recorded in the degree of bloodflow impairment in the muscles of patients treated with sulfanilurea drugs and insulin. Comparison of the degree of changes in the muscular bloodflow in diabetic angiopathies of the lower limbs and atherosclerosis obliterans of lower limb vessels in subjects without diabetes mellitus demonstrated that microcirculation in the former group patients was affected to a greater measure. It is desirable that the complex of therapeutic measures should include drugs that improve microcirculation at the early stages of the management of patients with diabetic angiopathies of the lower limbs.

Adult↗

PubMed1982

Effects of fluorocarbon infusion on microcirculation during cardiopulmonary bypass.

A pulsatile pump was used to effect a three-hour cardiopulmonary bypass in 15 mongrel dogs. During the bypass, Fluosol-DA (35%) infusion was used in lieu of homologous blood transfusions. The greater omentum was chosen as a model of extraorganic microcirculation, and its reaction to the infusion was observed. The omentum's microcirculation was not adversely affected by the Fluosol-DA (35%): no sludging, microthrombi, arteriovenous fistulas, plasma skimming, stasis, or other adverse findings were observed. The animals' oxygen consumption did not decrease, and the resistance of the systemic blood vessels, did not increase during the experiment, suggesting that the fluorocarbon infusion had no untoward effects on the microcirculation.

Animals↗

PubMed1980

[Microcirculation in cancer of the esophagus and cardial portion of the stomach under combined therapy].

Under study was the status of microcirculation in surgical and combination treatment (with radiotherapy) in patients with cancer of the esophagus and gastric cardia. The method of isotope semiresorption from the muscle depot (64) of patients and the arterio-venous difference for water after the technic of V. P, Kaznacheev and A. A. Dzizinski (26 patients) were employed. The state of microcirculation was found to be dependent on the degree of emaciation, preoperative telegamma therapy and the postoperative complications. The mostly impaired microcirculation was noted in emaciated patients with developing complication who were subjected to radiotherapy.

Adult↗

PubMed1980

[Photoelectronic recording of Evan's Blue influx into the blood vessels of tumors with selectively evoked hemostasis as compared to healthy tissue. Retardation of dye influx as a criterion of microcirculation inhibition (author's transl)].

The method of relative microcirculation measurement using Evan's Blue was further improved and results on applying this method to tumors treated with the Cancer Multistep Therapy (CMT) are reported. The microcirculation of these tumors decreased irreversibly below 1% of the value of healthy tissue. The strong, selective inhibition of microcirculation corresponds practically to the separation of the tumor from the organism. Recorded curves demonstrate that this strong inhibition can be achieved neither by hyperthermia nor by hyperglycemia alone, but only by combination of these both steps.

Animals↗

PubMed1995

[Dynamic function tests for detection of physiologic and pathophysiologic reactions in cutaneous microcirculation].

Functional tests simulating local stresses are especially suitable for the evaluation of physiological and pathophysiological patterns in the cutaneous microcirculation, particularly if combined with non-invasive methods such as laser-Doppler fluxmetry and oxygen tension measurements. Arterial occlusion (3 min) and local heating (up to 42 degrees C) are appropriate as stimuli to simulate specific local demands on the cutaneous perfusion similar to those produced by pressure, myokinesis, heat, and inflammation. When the current microcirculatory status is described the initial values (LDF and pO2) and their time-courses during each functional test can be used to determine the so-called post-stimulatory parameters. These-- corresponding to physiological equivalents--allow statements on the vascular reactivity towards hypoxia and ischaemia. Furthermore, dynamic performance parameters can easily be derived from the poststimulatory values. They describe the capacity of cutaneous microcirculation with regard to perfusion reserves and ischaemic tolerance in local stress situations in an appropriate manner. As an example of the usefulness of functional tests for cutaneous microcirculation, the physiological and pathophysiological patterns found in systemic sclerosis are described.

Blood Flow Velocity↗

PubMed1995

[Effect of topical timolol on the blood velocity of the iris microcirculation and the aqueous veins in human subjects].

To clarify the effect of topical timolol on the microcirculation in human eyes, the blood velocity changes of the iris microcirculation and the aqueous veins were measured before and 90 minutes after instillation of timolol in 8 eyes of 8 healthy volunteers by laser speckle flowgraphy. Systemic blood pressure, heart rate and intraocular pressure were measured before and 90 minutes after the instillation. The fellow eyes were measured as controls. The blood velocity decreased in the iris microcirculation (10% decrease, p < .05) and in the aqueous veins (8% decrease, p < .02) 90 minutes after instillation of timolol. The diameter of the aqueous veins did not change, so that the blood flow in the aqueous veins decreased (6% decrease, p < .02) after instillation. The intraocular pressure and pulse rate decreased (20 and 8% decrease, p < .002 and < .001, respectively) 90 minutes after the instillation. The blood velocity, vessel diameter, and intraocular pressure of fellow eyes and systemic blood pressure showed no significant change. These findings indicate that topical instillation of timolol induces decrease of blood flow in the iris, and, possibly, in the ciliary body. The instillation of timolol may decrease aqueous humor formation, and blood flow in aqueous veins.

Administration, Topical↗