Relations among activity, blood flow, and vascular state in skeletal muscle

Abstract

The relation between stimulus interval and performance of skeletal muscle was investigated under conditions of controlled and spontaneous blood flow. Vascular resistance, arteriovenous oxygen saturation difference, oxygen consumption, and peak isometric tension and blood flow were used as indices of muscle performance. In all cases vascular resistance decreased while oxygen consumption increased as the stimulus interval was shortened. The relative contributions of alteration flow (where permitted) and alteration of arteriovenous oxygen difference to changes in oxygen consumption were assessed. The latter proved to be the more important contributor. The apparent oxygen cost per unit of tension change rate decreased to a nearly steady level as the stimulus interval shortened. Changes in these variables brought about by intra-arterial infusion of acetylcholine or d-tubocurarine were shown. The results illustrate some features of the myovascular interaction which occurs during muscular activity. A model of the blood flow-oxygen consumption relation, based on considerations of oxygen extraction, is presented.