On the possible role of prostaglandin E2 in intestinal stasis in the gastric brooding frog Rheobatrachus silus.

Responses of isolated intestinal preparations from the anurans Bufo marinus and Limnodynastes tasmaniensis to various agents have been studied, as models for the intestinal stasis reported in the rare gastric brooding frog, Rheobatrachus silus. It is inferred from the responses that the preparations possessed excitatory muscarinic and histamine receptors and inhibitory adrenergic receptors, conforming to the typical vertebrate pattern. The circular muscle was unresponsive to prostaglandin E2, whereas longitudinal muscle relaxed to prostaglandin E2. Some of the longitudinal preparations exhibited a biphasic response to arachidonic acid, i.e. contraction followed by relaxation. Indomethacin prevented the relaxation phase, indicating that the intestine synthesised a prostaglandin E-like substance from arachidonic acid. These results draw attention to the possibility that PGE2 may be responsible for the intestinal stasis associated with gastric brooding in the gastric brooding frog.