Effects of Different Types of Vasodilator Mechanisms on Vascular Tonus and on Transcapillary Exchange of Diffusible Material in Skeletal Muscle

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Abstract
Pressure‐flow curves, representing various states of vascular tonus were obtained in isolated skeletal muscles of dogs and cats perfused with blood at constant flow. The arteriovenous (A‐V) extraction of rubidium‐86 was also continuously recorded. Metabolic vasodilatation and vasodilatation due to inhibition of the activity in the vasoconstrictor nerves induced a decrease of vascular tonus and an augmented blood‐tissue transport. Vasodilatation due to excitation of cholinergic vasodilator nerves produced a decrease in peripheral resistance amounting to about 70 per cent of the decrease caused by metabolic vasodilatation. Vasodilator nerve activity did not produce any consistent change in blood tissue transport. It is considered that vasodilator nerve activity produces an arteriolar dilatation, whereas vasodilatation due to inhibition of vasoconstrictor nerve impulses or followed by muscular contraction induces relaxation of smooth muscles in both arterioles and precapillary sphincters