[Changes in cholino- and adrenoceptors as affected by blood proteolytic enzymes]

The effects of kallikrein, thrombin, and plasmin on interaction of acetylcholine and noradrenaline with receptors of the isolated portal vein of guinea-pigs were studied. The functional activity of receptors was studied by the pharmacokinetic method. It was found that kallikrein and thrombin do not disturb the kinetics of agonist interaction with receptors, whereas the magnitude of isometric vascular contractions dramatically decreased after plasmin treatment and becomes disproportionate to the concentration of neurotransmitters. Exposure of the portal vein to kallikrein or thrombin caused different changes in the sensitivity and quantity of active cholino- and adrenoreceptors. These proteolytic enzymes reduced the sensitivity of receptors to noradrenaline and increased it to acetylcholine. Exposure to kallikrein brought about a decrease in the quantity of active cholinoreceptors and a rise in the number of adrenoreceptors. The treatment of the vessels with thrombin resulted in a decrease in the number of active adrenoreceptors. The number of active cholinoreceptors remained unchanged.