The Pressor Action of Guanethidine in the Spinal Cat

Abstract

Guanethidine has a marked pressor action in the spinal cat. Doses of 2–4 mg./kg. produce a greater increase in blood pressure than doses of 8–16 mg./kg. Large doses of guanethidine (16 mg./kg.) inhibit the pressor action of small doses (2 mg./kg.). Guanethidine potentiated the pressor action of noradrenaline but inhibited that of tyramine. The degree of inhibition of tyramine increased with the dose of guanethidine, but was inversely related to the pressor action of guanethidine.