Modification of drug responses by hydrolytic Enzymes

Abstract

α-Chymotrypsin and phospholipase enzymes have been used to alter the cell membranes of the smooth muscle of the guinea-pig taenia coli. The effects of these treatments on the electrical and mechanical responses of the muscle to acetylcholine have been studied. Prolonged treatment with both enzymes causes depolarization with a consequent loss of acetylcholine sensitivity. After controlled trypsinization a membrane response to acetylcholine was obtained in the absence of a mechanical response. The sensitivity of the taenia coli to acetylcholine was depressed by controlled phospholipolysis without affecting the membrane potential or contractile apparatus. The implications of these findings are discussed.