Effects of ethyl alcohol on canine jejunal circular smooth muscle

Ethyl alcohol has many symptomatic effects on the gastrointestinal tract. Our aim was to determine the effects of ethyl alcohol on circular smooth muscle contractility of the canine small bowel. Mechanical and intracellular electrical recordings were made in vitro from the circular muscle of full-thickness strips of muscularis externa from canine jejunum. Ethyl alcohol (20-120 mM) dose-dependently decreased spontaneous contractile amplitude, hyperpolarized the resting membrane potential, and decreased the amplitude of the slow wave. Ethyl alcohol also decreased the amplitude of the inhibitory junction potential (during electrical field stimulation-EFS) but did not alter the maximum absolute cell-polarized potential reached during EFS. An increase in extracellular calcium (15 mM) partially restored spontaneous contractile amplitude, resting membrane potential, and slow-wave amplitude. Ethyl alcohol decreased the amplitude of contractions evoked by acetylcholine, CCK, and substance P. These data suggest that ethyl alcohol has direct effects on jejunal smooth muscle contractility. These effects can be partially reversed by increasing the availability of extracellular calcium.