Effects of acetaldehyde on electrical and mechanical activities of guinea-pig taenia coli.

The effect of acetaldehyde on the electrical and mechanical activities of the isolated segment of taenia coli from guinea-pigs has been studied using a sucrose-gap method. Application of acetaldehyde produces relaxation of the muscle, which is accompanied by reduction or cessation of spontaneous spike activity and hyperpolarization of the membrane. The hyperpolarization becomes smaller with lowering the temperature. These actions of acetaldehyde are not modified by adrenergic and cholinergic receptor blocking agents nor by tetrodotoxin and ouabain. Acetaldehyde also reduces the evoked activities produced by KCl, BaCl2, acetylcholine or electrical stimulation. The nonadrenergic inhibitory junction potential is reduced by acetaldehyde. When external Ca++ is replaced with Sr++ or Ba++, the action of acetaldehyde is suppressed. Addition of Mn++ eliminates the action of the aldehyde. Acetaldehyde relaxes the muscle when administered after fully developed membrane depolarization induced by K2SO4.