Objective: The purpose of this investigation was to determine the effect of decreased perfusion pressure (Pperf.) on the dilatation and normalisation processes of skeletal muscle vessels.

Methods: Ten healthy subjects were investigated in supine position. Blood flow (I) and oxygen consumption (VO2) were studied during reactive hyperemia (RH) caused by arterial occlusion (AO) of 30 sec., 1, 3, 5, 7, 15 and 30 min. in the forearm at the level of the heart and after passive raising the arm above heart level. I was determined by venous occlusion plethysmographic method. VO2 was determined according Fick principle. Total cross-sectional area of forearm blood vessels (Q) was calculated.

Results: Analysis of the forearm I and VO2 in the discrete points of determination during RH revealed that raising the arm above heart level evoked the decrease of maximal values of I and VO2 in the early phase of RH, but further these values becomes greater than those in the horizontal arm position. Comparison of maximal values of forearm Q revealed that the reduction of Pperf. did not affect dilatation process of skeletal muscle precapillary vessels, but caused a delay of Q normalisation during RH.

Conclusions: Dilatation and normalisation processes of skeletal muscle precapillary vessels are two different phenomenons which are determined by different local factors. Dilatation reaction of precapillary vessels is determined by disappearing of dynamic component of transmural pressure after AO, but normalisation of resistance vessel tone is dependent from the repayment of O2 debt and blood supply conditions during RH.