In many developed countries the prevalence of venous disorders and its consequences are higher than that of arterial diseases. Thus it is very important to understand the exact physiological and pathophysiological function of small veins and their control mechanisms. Small veins and venules have an important role in the regulation of capillary fluid exchange, as well as return of the venous blood into the heart. However, there is only limited knowledge available regarding the role of local mechanisms controlling the vasomotor tone and diameter of small veins. In the last decade the authors focused on the elucidation of these mechanisms in isolated skeletal muscle venules of rats. Their results suggest that the tone of small veins is controlled by the integration of several mechanisms, activated by the intraluminal pressure and flow/wall shear stress, in addition to numerous local mediators synthesized and released from the smooth muscle and endothelium. These mechanisms are involved - in a complex manner - in the control of postcapillary resistance, thus regulation of tissue blood supply, venous return and consequently in the modulation of the cardiac output, as well.
Keywords: arachidonic acid; arachidonsav; endothelium; flow/wall shear; hidrogen peroxide; hidrogén-peroxid; nitric oxide; nitrogén-monoxid; nyomás; nyíróerő; patkány; pressure; prostaglandins; prosztaglandinok; rat; sceletal muscle venule; tromboxane A2; tromboxán-A2; vasomotor tone; vazomotortónus; vázizomvenula.