The purpose of the present work was to investigate the changes of spontaneous and induced contractility in the rat vena porta, in conditions of acute pancreatitis, artificial trypsinemia and direct action of trypsin. The amplitude, frequency and mainly the intensity of the structure functioning decrease significantly under the influence of proteolitic enzymes (trypsin). The contractility of the isolated portal vein decrease in reply of the increase or decrease of the concentration of Ca2+ ions. Thus the possible action mechanism of proteolitic enzymes action consists in damaging at the sarcolemma, which causes the decrease in the influx of Ca2+ ions during the action potential.