title: Effects of acetaldehyde on the membrane resistance in the smooth muscle of the guinea-pig taenia caecum.
abstract: The action of acetaldehyde on the membrane resistance of the guinea-pig taenia caecum was investigated with a double sucrose-gap method in different ionic environments. Application of acetaldehyde (10--20 mM) produced hyperpolarization, block of spike discharge and reduction of the membrane resistance. The reduction of the membrane resistance by acetaldehyde was potentiated by increasing the external K+ concentration and by replacement of Cl- with NO3-; it was reduced by lowering the external K+ concentration and by replacement of Cl- with benzenesulfonate. Replacement of NaCl with Tris-Cl, sucrose, or LiCl had no appreciable effect on the action of acetaldehyde on the membrane resistance. It therefore seemed likely that acetaldehyde increased the membrane conductance for K+ and Cl- more than for Na+. Although this action of acetaldehyde was similar to the alpha-action of catecholamine, the decrease of the membrane resistance and hyperpolarization induced by acetaldehyde remained unchanged in the presence of phentolamine.
mesh_terms: D000079:Acetaldehyde / Q000494:pharmacology*; D000818:Animals; D002712:Chlorides / Q000494:pharmacology; D003106:Colon / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D010646:Phentolamine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology
chemical_list: D002712:Chlorides; D012964:Sodium; D000079:Acetaldehyde; D011188:Potassium; D010646:Phentolamine