[Changes in plasma composition resulting in an increase in the osmotic pressure of venous blood during the cholinergic dilatation effect].

Stimulation of the sympathetic chain in the presence of alpha-receptor blocking agents caused cholinergic vasodilatation of the cat hind-limb vessels. The arterial-venous difference with respect to osmotic pressure (Posm), as well as to the content of K+, Na+, Ca2+, lactate, total protein, and inorganic phosphate was determined in blood samples collected during vasodilatation. Sympathetic stimulation in the presence of alpha-receptor-blocking agents agents increased the conductance of the hind-limb vessels and Posm of the venous blood (7.6 +/- 0.8 mOsm/l); both effects were abolished by atropine. During vasodilatation the content of K+, Na+ and lactate in venous blood plasma was increased, while that of total protein, inorganic phosphate and Ca2+ remained unchanged. The increase in Posm (73.7%) was found to be due to the rise in Na+. The data obtained suggest an increased intensity of metabolism in skeletal muscle during cholinergic vasodilatation.