Effects of tachykinins on the splanchnic circulation: a comparison of the dog and rat.

Responses to the administration of graduated doses of tachykinins were examined in various vascular beds of the dog. Among the tachykinins, all vascular beds studied demonstrated that the greatest vasodilation responses was produced by substance P. However, each tachykinin demonstrated a specific pattern of response. With substance P the greatest sensitivity was seen in the superior mesenteric artery (SMA), with neurokinin B in the celiac axis, and with neurokinin B a prolonged vasodilation response of the SMA compared to the other two vessels was seen. The response to substance P in the SMA of the rat was considerably less than that of the dog.