SEARCH · PubMed Health

Results for “Microcirculation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,729 records · Page 96Linked to original sources

PubMed1999

New techniques for clinical assessment of the peripheral microcirculation.

Current methods for clinical investigation of the cutaneous microcirculation in patients are based mainly on laser Doppler and capillary microscopy. The use of laser Doppler gives a semi-quantitative index of superficial tissue perfusion. The most recent devices are capable of analysing both the volumetric and velocimetric components. New instruments use two different frequencies to compare tissue perfusion at different depths beneath the skin surface. The combination of a laser probe and a small automate produces a 2-dimensional image, allowing the evaluation of spatial heterogeneity in tissue perfusion, an important pathophysiological concept in vascular diseases. Capillaroscopy has recently been improved by the emergence of the flexible videomicroscope, allowing easy exploration of not only the classical site of the nail-fold but also of the body skin surface. The use of this method was therefore extended--from peripheral vascular disease and connective tissue diseases to the whole spectrum of trophic changes in the skin of the extremities. Systems for digital image analysis allow quantification of the structure of the microvascular bed (quantitative appraisal of microangiopathies) and function (capillary haemodynamics and exchange). Laser Doppler and capillaroscopy can also be combined for the measurement of red blood cell velocity in single capillaries.

Blood Flow Velocity↗

PubMed1999

Intravital microscopy for the study of the microcirculation in various disease states.

The study of the microcirculation by intravital microscopy represents a sophisticated research tool to analyse complex biological interactions and disease mechanisms as well as to develop and test novel prophylactic and therapeutic approaches aimed at the prevention or attenuation of manifestation of disease-associated microvascular disorders and cellular dysfunction. This may include pathogenesis of atherosclerosis and thrombosis, fibrosis and cirrhosis as well as hypertension, diabetes and tumorogenesis. In addition, using the microscopic technique, circulatory and cellular disorders in surgical diseases and procedures, such as shock and resuscitation, ischaemia/reperfusion and transplantation, trauma, sepsis and inflammation, as well as burn injury and wound healing, may be analysed. With the background of the increasing knowledge of molecular and cellular mechanisms of disease evaluated in vitro, the technique of intravital microscopy ideally allows to bridge over from those in vitro observations to test their potential relevance in vivo.

Animals↗

PubMed1999

In vivo assessment of synovial microcirculation and leukocyte-endothelial cell interaction in mouse antigen-induced arthritis.

OBJECTIVE: The microcirculation and leukocyte-endothelial cell interaction in synovial tissue of an inflamed joint are known to play a crucial role in the pathogenesis of rheumatoid arthritis. The aim of this study was to characterize the in vivo changes in the microvasculature and in leukocyte-endothelial cell interactions in the mouse synovial tissue using intravital fluorescence microscopy in three stages of antigen-induced arthritis. The expression of E- and P-selectin and ICAM-1 were also studied using immunohistochemistry. METHODS: Antigen-induced arthritis (AiA) was produced in Balb/c mice. The severity of arthritis at three different phases was quantified using a clinical and histological score. For the intravital fluorescence microscopy measurements, the patella tendon was partially resected for visualization of the intraarticular synovial tissue of the knee joint. The number of rolling and adherent leukocytes, functional capillary density (FCD) and RBC velocity were quantitatively measured in synovial microvessels. Expression of ICAM-1, E- and P-selectin was assessed by immunohistochemistry. RESULTS: There was a significant increase in the leukocyte rolling fraction in postcapillary venules in the acute phase of AiA (from 0.26 +/- 0.05 in controls to 0.45 +/- 0.04 8 d after AiA induction). The number of leukocytes adherent to the endothelium was significantly elevated in all phases of arthritis (from 121 +/- 27 in controls to 376 +/- 62 mm2 63 d after AiA-induction). Functional capillary density was significantly enhanced in the acute (332 +/- 15 cm/cm2) and intermediate phases (320 +/- 15 cm/cm2) compared to control values (227 +/- 15 cm/cm2). Arthritis resulted in a distinct increase in the expression of ICAM-1 on the synovial endothelium in all phases of AiA. E- and P-selectin expression were detected only in the acute phase. CONCLUSION: Our model provides new insights into the microcirculatory changes which occur in the synovial tissue of an arthritic joint.

Animals↗

PubMed1976

Microcirculation of the renal papilla of rats under control conditions and after temporary ischemia.

Blood flow velocities were measured and, with the help of vessel diameters, volume flow rates were calculated in the ascending and descending vasa recta of the renal papilla of young rats using microkymography. Measurements were done under control conditions, and one or three days after temporary ischemia of the kidney (one hr of renal artery occlusion). To test whether the osmolality of the final urine which surrounds the papilla influences the papillary microcirculation, the papillary surface was rinsed with 300 or 1500 mOsm solutions. However, the rinse fluid osmolality had no effect on blood flow. Flow velocity in descending vasa recta(hypertonic rinse fluid) averaged 0.60 +/- 0.04 SEM mm/sec under control conditions, 0.68 +/- 0.08 mm/sec one day after temporary ischemia, and 0.73 +/- 0.04 mm/sec three days after temporary ischemia. The corresponding blood flow rates are 9.3 +/- 1.0, 8.3 +/- 1.2, and 10.5 +/- 1.5 nl/min; these values are not significantly different from each other. Flow rate in the ascending vasa recta was 6.4 +/- 0.6 nl/min under control conditions and 9.3 +/- 1.2 nl/min one day postischemia. The significance increase in ascending vasa recta blood flow after ischemia was probably due to an increase in the permeability of the papillary epithelium. An exact quantitative comparison between blood inflow and outflow from the papilla is not possible at present, because it is not yet clear to what extent the number of ascending vasa recta outnumber the descending vasa recta.

Animals↗

PubMed2000

Therapeutic effects of Aloe vera on cutaneous microcirculation and wound healing in second degree burn model in rats.

OBJECTIVE: To demonstrate the microcirculatory and wound healing effects of Aloe vera on induced second degree burn wounds in rats. METHOD: A total of 48 male Wistar rats were equally divided into 4 groups as follows: sham controls, untreated burn-wound rats, those treated with once-daily application of normal saline (NSS) and those treated with once-daily application of lyophilized Aloe vera gel. The animals in each group were equally subdivided into 2 subgroups for the study of cutaneous microcirculation and wound healing on day 7 and 14 after burn. Dorsal skinfold chamber preparation and intravital fluorescence microscopic technique were performed to examine dermal microvascular changes, including arteriolar diameter, postcapillary venular permeability and leukocyte adhesion on postcapillary venules. RESULTS: On day 7, the vasodilation and increased postcapillary venular permeability as encountered in the untreated burn were found to be reduced significantly (p < 0.05) in both the NSS- and Aloe vera-treated groups, but to a greater extent in the latter. Leukocyte adhesion was not different among the untreated, NSS- and Aloe vera-treated groups. On day 14, vasoconstriction occurred after the wound had been left untreated. Only in the Aloe vera-treated groups, was arteriolar diameter increased up to normal condition and postcapillary venular permeability was not different from the sham controls. The amount of leukocyte adhesion was also less observed compared to the untreated and NSS- treated groups. Besides, the healing area of the Aloe vera-treated wound was better than that of the untreated and NSS- treated groups during 7 and 14 days after burn. CONCLUSION: Aloe vera could exhibit the actions of both anti-inflammation and wound healing promotion when applied on a second degree burn wound.

Administration, Topical↗

PubMed2000

Influence of dopexamine on hemodynamics, intramucosal pH, and regulators of the macrocirculation and microcirculation in patients undergoing abdominal aortic surgery.

OBJECTIVE: To investigate whether dopexamine hydrochloride beneficially influences splanchnic perfusion and regulators of the macrocirculation and microcirculation in patients undergoing surgery of the abdominal aorta. DESIGN: Prospective, blinded, and randomized study. SETTING: University-affiliated hospital. PARTICIPANTS: Twenty patients undergoing elective abdominal aortic surgery. INTERVENTIONS: The patients were randomized to one of two groups. In the dopexamine group (DOP, n = 10), dopexamine, 1 microg/kg/min, was started before surgery and continued for 24 hours. In the control group (COG, n = 10), patients received saline solution as placebo. Extensive hemodynamic monitoring was carried out using a pulmonary artery catheter, and intramucosal pH was measured using a gastric tonometer. From arterial blood samples, important regulators of the circulation were measured before dopexamine was administered (T0), before aortic clamping (T1), 20 minutes after aortic clamping (T2), after declamping the first leg (T3), at the end of surgery (T4), 1 hour postoperatively (T5), and 24 hours postoperatively (T6). MEASUREMENTS AND MAIN RESULTS: Heart rate increased significantly in DOP (63+/-16 to 84+/-18 beats/min). At T5, mean pulmonary artery pressure was significantly lower in DOP (15+/-6 mmHg) than in COG (22+/-6 mmHg). During aortic clamping, pulmonary capillary wedge pressure increased significantly in both groups. Cardiac index increased significantly from baseline only in the dopexamine patients. No significant differences between the groups were seen with regard to oxygenation parameters and intramucosal pH. Renin plasma levels increased significantly only in COG (46+/-32 to 99+/-55 microU/mL). Endothelin and atrial natriuretic peptide plasma levels showed no significant differences between the two groups. Atrial natriuretic peptide increased significantly only in DOP (366+/-171 pg/mL; COG, 159+/-71 pg/mL). Antidiuretic hormone, norepinephrine, and epinephrine plasma levels increased significantly from baseline in both groups, without showing significant differences between the groups. CONCLUSIONS: In patients undergoing abdominal aortic surgery, prophylactic perioperative administration of dopexamine hydrochloride produced effects on hemodynamics but without improving oxygenation and intramucosal pH. From the measured regulators of the circulation, only renin was beneficially affected.

Adult↗

PubMed2000

[Tumor microcirculation and selective enhancement of drug delivery--clinical applications based on pathophysiological experiments].

Tumor tissue is composed of cancer cells (parenchyma) and tumor vessels (interstitium). Many investigators have pointed out that blood flow in tumors has a very inhomogenous distribution, and that this inhomogeneity in blood flow increases as tumors grew. This would be a certain cause of insufficient drug delivery to tumor tissues. Among the experimental evidence using Yoshida Sarcoma and Ascites Hepatomas, functional differences in microcirculation between tumor and normal tissues were found by Suzuki et al. (1977). Under hypertensive state induced by the continuous infusion of angiotensin II, tumor blood flow increased remarkably, while there was no change or decrease in blood flow in normal tissues such as the brain, bone marrow, liver and kidney. Moreover, the increase in blood flow in tumors was selective, as the mean blood pressure remained at the level of 150 mmHg. Increases were confirmed not only in many growing sites such as in the liver, muscle, subcutis, and even microfoci, but also in various kinds of xenografted human tumors and autochthonous tumors. Augmentation of the anti-tumor effects of angiotensin II-induced hypertension chemotherapy (IHC) for advanced gastric carcinoma was revealed in two randomized controlled trials (RCT-1 & 2) of collaborative study groups in Japan. The response rates were 42.9% vs 10.5% in RCT-1 and 31.3% vs 6.7% in RCT-2. The frequencies of toxicities were not statistically different. In the results of phase II studies from 1978 to 1994 (OPN-1) and 1995 to 1999 (OPN-2) for advanced gastric carcinoma (GC), the response rates were 37.9% and 35.7%. Down staging in which the conclusive stage score was lower than the score of the clinical stage, was observed in 8 out of 94 cases (19%) with primary lesions in total and in 30 patients (63%) receiving reduction surgery after IHC, since 1978. It is very important for exact evaluation after chemotherapy to understand or estimate the pathohistological changes in the tumor and its degenerated or repaired tissues, which present various clinical images. In the present study, the actual administered dose intensity of adriamycin (aDIadm) was 5.9 +/- 2.4 mg/sqm/w, and the ratio of aDIadm to the proposed DIadm of reported FAM/FAP schedules was 0.78 +/- 0.32. IHC with smaller DI could lead to a reduction in the accumulation of toxicities of anti-cancer drugs in the host. In conclusion, IHC might be applied to all kinds of tumors to enhance the chemotherapeutic effects through selective increase of drug delivery to tumors.

Animals↗

PubMed2000

[Dysfunction of the coronary microcirculation in type 2 diabetic patients].

A failure of coronary blood flow to increase during cold pressor test has been shown in patients with coronary atherosclerosis and impaired metabolic coronary vasodilatation in response to atrial pacing has been demonstrated in diabetic patients without significant epicardial artery stenoses. This study was designed to evaluate coronary microvascular adaptation to increased myocardial oxygen demand in response to sympathetic stimulation in diabetic patients with angiographically normal coronary arteries. Microvascular coronary adaptation to increased myocardial oxygen demand due to sympathetic stimulation evoked by the cold pressor test has been examined in 22 type 2 diabetic patients and in 15 control subjects with angiographically normal coronary arteries and no other risk factors. Coronary blood flow was calculated by measuring mean flow velocity in left anterior descending coronary artery by intracoronary Doppler and cross sectional area of the artery by digital angiography. Results show that despite a similar increase in rate-pressure product in the 2 groups (+22.6 +/- 12.4% in diabetic patients and +31.8 +/- 8.2% in control subjects, NS), coronary blood flow increase in left anterior descending artery was significantly lower in diabetic patients than in control subjects (+14.7 +/- 19.8% vs +75.5 +/- 13.5%, respectively, p = 0.0001). In addition, when there was a positive correlation between the 2 parameters in control subjects (R = 0.651, p < 0.01), there was no relationship in diabetic patients (R = 0.054). In conclusion, this study demonstrates that vasodilatation of coronary microcirculation in response to sympathetic stimulation evoked by cold pressor test is impaired in type 2 diabetic patients without epicardial artery lesions. This microvascular impairment during sympathetic stimulation may explain exercise-induced myocardial perfusion abnormalities observed in these patients and may impair microcirculatory coronary vasodilatation during current life stress episodes such as exercise, mental stress or cold exposure.

Adaptation, Physiological↗

PubMed2000

Role of microcirculation in transplantation.

Microcirculatory derangements in organ transplantation, characterized by capillary perfusion failure and inflammation-associated leukocyte recruitment, are major determinants for the manifestation of graft dysfunction and destruction. Although preservation/cold storage, posttransplant reperfusion, and rejection have to be considered as individual factors that contribute to injury, recent studies have indicated that ischemia-reperfusion-associated events may trigger immune-response-mediated late rejection. There is major evidence that the microcirculatory derangements induced by cold preservation and reperfusion involve oxygen radicals, complement, phospholipase A2, leukotrienes, thromboxane, platelet-activating factor, and endothelin-1 as well as the activation and function of leukocytic and endothelial selectins, beta 2-integrins, and ICAM-1. This view is based on the fact that blockade or neutralization of these inflammatory mediators and adhesion molecules results in significant amelioration of microvascular graft dysfunction. In parallel, rejection-mediated microcirculatory derangements may not only be ameliorated by immunosuppressive agents, such as cyclosporin, deoxyspergualin, or RS61443, but may, in addition, effectively be inhibited by counteracting oxygen radicals, complement, platelet-activating factor, and adhesion molecules. The introduction of novel techniques for the study of the microcirculation in men, such as thermodiffusion and orthogonal polarization spectral imaging, may in the future assist in improving both early diagnosis of microcirculatory derangements and monitoring of appropriateness of therapy in clinical transplantation surgery.

Animals↗

PubMed1999

Correlation between retinal microcirculation and blood viscosity in patients with hyperviscosity syndrome.

Hyperviscosity syndrome leads to vascular disturbances in different organs. In the retina typical ophthalmoscopic changes can be found including dot and blot hemorrhages, retinal and optic nerve head edema, and increased diameter of retinal veins. In this study we examined the retinal microcirculation in patients with hyperviscosity syndrome. Nineteen patients (14 patients with Waldenstroem's macroglobulinemia, two patients with kryoglobulinemia, three patients with plasmacytoma) were examined. All patients underwent a video fluorescein angiography. In all angiograms the arteriovenous passage time (AVP) and the arm retina time (ART) were quantified. In addition, hematocrit (Hct) and plasma viscosity (ETA) were measured. In patients with hyperviscosity syndrome AVP was significantly prolonged in comparison to healthy volunteers (AVP: 2.5+/-1.3 s vs. 1.5+/-0.4 s; p < 0.01). The ART showed no significant differences. Plasma viscosity was doubled in patients as compared with reference values (ETA: 2.57+/-1.5 mPa s vs. 1.24+/-0.08 mPa s; p < 0.01). In this study we showed an increase in plasma viscosity as well as an increase in arteriovenous passage time. This may result in retinal circulatory disturbances and may cause the typical fundus changes in patients with hyperviscosity syndrome.

Adult↗

PubMedDate not supplied

[Blood gas analysis of forearm veins--at rest and after exercise of forearm muscles and laser Doppler flowmetry of skin on the back of the palm--use in evaluation of microcirculation in diabetes type 2].

The aim of the study was to compare of nondominant forearm microcirculation in adult-type diabetes and healthy subjects with use of venous blood gasometry (vbg) sampled from basilic vein before and after exercise of antebrachial muscles and with use of laser doppler fluxometry (LDF) with optode localized in dorsal palm surface. Examinations were performed in groups of 16 diabetic patients (aged 43.5 +/- 5.7) and 16 healthy subjects (aged 39.3 +/- 7.8). After exercise of antebrachial muscles in diabetic patients in vbg were: pH higher, pO2 and satO2 lower than in healthy subjects, pCO2 and -HCO3 were not different in both group. In LDF in diabetic patients impaired hypraemic reaction, impaired heating to 40 degrees C reaction and hyperaemic reaction in this temperature were found.

Adult↗

PubMed2000

[Photoplethysmographic evaluation of microcirculation in patients with overt and latent hyperthyroidism or hypothyroidism].

Alterations in the finger microcirculation in patients with disturbed function of the thyroid gland was evaluated with planimetric photoplethysmography. One-hundred forty-one patients with disturbed thyroid function (31 overt hyperthyreoidism, 10 latent hyperthyreoidism, 79 overt hypothyreoidism, 22 latent hypothyroidism) and 30 healthy individuals were investigated. Serum free thyroxine and thyreotropine level were determined in all investigated subjects. The systolic-diastolic index (SDI) was measured in all individuals with photopletysmography. A decrease in SDI was found in the patients with hyperthyroidism (overt 0.121; latent 0.158) and an inverse in SDI was shown in hypothyroid patients (overt 0.617; latent 0.471) was compared with the controls (0.345). SDI correlated with serum free thyroxine and thyreotropine levels and clinical symptoms.

Adult↗

PubMedDate not supplied

Effects of intra-arterial administration of prostaglandin E1 on rat cremaster muscle microcirculation.

In plastic and reconstructive surgery, postoperative drug therapy with prostaglandin E1 (PGE1) has been widely used to prevent flap necrosis and to extend flap surviving area. In the present study, we assessed the effects of intra-arterial administration of PGE1 on microcirculation. The left cremaster muscle of male Wistar rats were used to measure microcirculatory hemodynamic parameters. The values of internal vessel diameter and erythrocyte velocity were measured by using the confocal laser-scanning microscope (CLSM) system and fluorescent dyes. The blood flow rate was calculated from measured internal vessel diameter and erythrocyte velocity. Internal vessel diameter and flowing erythrocytes were satisfactorily visualized by using the CLSM system. The blood flow rate of arteriole, venule and capillary were dose dependently increased by the intra-arterial administration of PGE1 from the minimum dose of 0.01 ng/kg/min. It is suggested that the intra-arterial administration of PGE1 is a more effective way of postoperative drug therapy than intravenous injection for flap surgery.

Alprostadil↗

PubMed2000

Pathophysiology of microcirculation in venous disease.

Microcirculatory disturbances lead to chronic ulceration of the leg, and this symptom is a sign of a chronic venous insufficiency (CVI), caused by increased leg vein pressure and continous changes in vein pressure, which need medical treatment, and if a chronic capillary reaction present, treatment by applying a graduated compression bandage of the leg is mandatory. Subcutaneous tissue hypoxaemia and interstitial edema lead to worsening of the ulcer and need intensive and systematic wound care, because unhealed chronic wound with trophic changes of the skin is the major cause of further CVI changes of the leg. As chronic venous disease has complex etiologic basis, it needs diagnostics and treatment modality based on various approaches, and that microcirculatory pathophysiological approach should be considered in all kinds of the treatment of chronic venous insufficiency. Microcirculation pathology should be used as an approach in the treatment regiment of CVI, whilst the basic pathophysiology of the venous diseases, which is known as one of the causes of CVI. This approach will give better results of treatment and other pathologic disturbances which were caused by chronic vitious circle chain processes.

Bandages↗

PubMed2000

Local regulators of hepatic sinusoidal microcirculation: recent advances.

This article reviews our recent studies on the local regulation of hepatic microcirculation with special reference to the inlet sphincter-like structures, the roles of sinusoidal endothelial cells and the mechanism of dynamic changes in the sinusoidal endothelial fenestrae (SEF) as well as in the terminal portal venules and the terminal hepatic arterioles induced by the potent vasoconstrictor endothelin (ET)-1. There are two types of sphincter-like structures at the entering sites of hepatic sinusoids. One is located at the junction between the terminal portal venule and the sinusoid, and is characterized by the large endothelial cells surrounded with Ito cells (hepatic stellate cells: HSCs). The other is located at the junction between the terminal hepatic arteriole and the sinusoid, and corresponds to the precapillary sphincter since our enzymohistochemical demonstration of arterial capillaries in close association with the sinusoids combined with intravital microscopy has revealed that the terminal hepatic arteriole directly terminates in the sinusoid. It is essential for the local control of hepatic sinusoidal blood flow that the dynamic contracting and relaxing changes not only in these inlet sphincter-like structures but also in the SEF correspond with those of the HSCs, both of which are mediated by the sinusoidal endothelium-derived vasoconstrictor endothelins (ETs) and vasodilator nitric oxide (NO). The contractility of the SEF and HSCs depends on the intracellular Ca++-calmodulin-actomyosin system.

Actomyosin↗

PubMed2001

Mechanisms for cell activation and its consequences for biorheology and microcirculation: Multi-organ failure in shock.

Activation of cells in the vascular compartment causes profound alteration of cell rheological properties with impairment of the microcirculation and initiation of inflammatory reactions. Many cardiovascular diseases have been shown to be associated with cell activation and inflammation. While this situation offers the opportunity for new interventions against the deleterious effects of cell activation, there is the need for a better understanding of the mechanisms that lead to cell activation in the first place. We review here several mechanisms for cell activation in the circulation. We show that in shock, a condition associated with severe forms of cell activation, humoral cell activation factors can be detected in plasma. Further analysis indicates that the source of these humoral activators may be due to the action of pancreatic digestive enzymes in the intestine. Ischemia may serve to open the intestinal brush border and permit entry of pancreatic enzymes into the wall of the intestine to initiate self digestion. In this process low molecular weight but potent cell activators are produced which may escape via the intestinal circulation and the lymphatics into the general circulation. Inhibition of pancreatic enzymes in the lumen of the intestine leads to complete attenuation of humoral activator production as well as many of the deleterious sequelae that accompany shock, such as inflammation and multi-organ failure. We outline a method to carry out biochemical isolation of the cell activators derived from pancreatic enzymes. This analysis shows that there are multiple species of cell activators above and beyond currently known species, many of which have molecular weights below 3000 Da. Identification of the mechanisms that lead to cell activation is an important part to understand the mechanisms that lead to alterations of rheological properties of blood cells in disease and dysfunction of the endothelium and parenchymal cells. Our current evidence suggests that pancreatic digestive enzymes and tissue enzymes may play a central role in humoral activator production.

Animals↗

PubMedDate not supplied

Suppression of basal NO- and prostacyclin-dependent tone in cerebral microcirculation during chronic hyponatremia in female rats.

BACKGROUND: Our previous studies in the rat model of chronic hyponatremia have demonstrated the decrease of cerebral blood flow along with the attenuation of cerebral metabolic rate for oxygen exclusively in females and when hyponatremia was induced with vasopressin. Present study was designed to verify the hypothesis that the decrease of cerebral blood flow during chronic vasopressin-induced hyponatremia in female rats is due to the attenuation of basal vasodilator tone produced in cerebral microcirculation under physiological conditions by shear-stress-dependent release of nitric oxide and prostacyclin. MATERIAL AND METHODS: The experiments were performed on 47 anesthetized and mechanically ventilated adult, female Wistar rats. Chronic hyponatremia (3.5 days) was induced in these rats by the twice-daily subcutaneous administration of vasopressin (AVP) in conjunction with 140 mmol/L glucose/water solution. Cerebrocortical microflow (LDF) was monitored using laser-Doppler probe. LDF responses to the administration of either NG-nitro-L-arginine methyl esther (L-NAME, 30 mg/kg i.v.), indomethacin (INDO, 6 mg/kg i.v.), acetylcholine (ACh, 10 Kl/20 Kl/min ica) or 5% CO2 were tested in normonatremic and hyponatremic rats. RESULTS: The response of LDF to L-NAME, INDO and ACh were abolished in rats with hyponatremia. In contrast, CO2 reactivity was well preserved. CONCLUSIONS: Our results demonstrate that attenuation of cerebral blood flow during chronic AVP-induced hyponatremia in female rats is, at least in part, due to the withdrawal of basal vasodilator tone produced in cerebral circulation under physiological conditions by nitric oxide and prostacyclin.

Animals↗

PubMed2001

[Methods for in vivo investigation of human microcirculation].

Microcirculatory disorders play a major role in the development of organ failure in a variety of conditions. Perfusion changes may be visualized by static and dynamic methods, with direct and indirect techniques. Orthogonal polarization spectral imaging is a novel method of imaging the human microcirculation. The technique employs reflected light without fluorescent dyes and allows clinical assessment of the dynamic of the microvascular network of internal solid organs. Principles of the technique and indications of use are briefly discussed.

Capillaries↗