Electromyography of the Stomach and Small-Intestine of the Tammar Wallaby, Macropus-Eugenii, and the Quokka, Setonix-Brachyurus

Abstract

Electromyographic activity recorded by chronically implanted bipolar electrodes showed the tammar wallaby (Macropus eugenii) and the quokka (Setonix brachyurus) to have slow wave activity over the entire stomach and small intestine. Slow wave mean frequency (min-') were: 5.5 and 5.3 for the forestomach; 5.4 and 5.0 for the pylorus; 26 and 17.8 for the duodenum; and 25 and 17.5 for the ileum in the tammar and quokka, respectively. There was virtually no frequency gradient of the slow wave along the length of the small intestine in both macropods, which is extremely unusual. Action potentials were recorded from the quokka stomach but not from the tammar stomach. Action potentials were recorded from the small intestine of both species. The pattern of action potential activity was similar in both species. There were periods of up to 30 minutes during which the intestine was quiescent (q) with no action potential activity. This was followed by extended periods when bursts of action potentials occurred irregularly to be followed by periods of about 5 minutes when action potentials were associated with every slow wave.