Effects of electrical stimulation on the enkephalins in guinea-pig small intestine

When myenteric plexus-longitudinal muscle preparations of the guinea-pig small intestine are stimulated electrically in the presence of cycloheximide there is a decrease in the content of enkephalins which is taken to be due to their release. With supramaximal stimuli, the release per pulse is similar at 1 and 10 Hz but it is lower with submaximal than with maximal stimuli. Met-enkephalin is more readily released than Leu-enkephalin.