Autoregulation of Capillary Hydrostatic Pressure in Skeletal Muscle during Regional Arterial Hypo‐ and Hypertension

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Abstract
Net transcapillary fluid movements in the sympathectomized cat skeletal muscle were observed in response to regional mean arterial pressure variations in the range from 30 to 170 mm Hg. The transcapillary Starling fluid equilibrium prevailing at normal perfusion pressure was found to be roughly maintained over the entire range of arterial hypo‐ and hypertensions, indicating an approximate constancy of capillary hydrostatic pressure (pc). This “autoregulation of pe” was mainly due to active changes of vascular tone in the precapillary resistance vessels causing a resetting of the pre‐ to postcapillary resistance ratio (ra/rv), but disappeared after abolition of vascular tone by papaverine. In the lowest pressure range, a passive rise of postcapillary resistance contributed to the resetting of ra/rv. By this autoregulation of pc the muscle tissue is protected against undue redistributions of fluid between the intra‐ and extravascular spaces when arterial pressure per se is changed.