In vitro release and tissue levels of ileal serotonin after cisplatin-induced emesis in the cat.

We have studied the peripheral mechanisms responsible for the severe vomiting observed in cisplatin treated cats. Release of 5-hydroxytryptamine from isolated portions of the ileum and ileal tissue concentrations of 5-hydroxytryptamine were studied in vitro with control animals and animals previously treated with cisplatin. In the latter, two groups were observed: animals in which cisplatin (single dose, 10 mg/kg) induced vomiting within 4 h and animals that did not vomit within 4 h. Spectrofluorimetric assessment of 5-hydroxytryptamine in the perfusate and ileal tissue revealed that cisplatin increases both release, and tissue levels, of ileal 5-hydroxytryptamine in animals which vomited, whereas only ileal 5-hydroxytryptamine release was increased in animals which did not vomit. This may have clinical implications as cisplatin induced emesis may be more effectively prevented by drugs preventing ileal 5-hydroxytryptamine formation rather than release.