Central and peripheral contribution to the antihypertensive action of indoramin.

Indoramin has been reported to reduce blood pressure in experimental animals and humans. The complex pharmacological profile of the compound suggests that it may also exert central actions. Effects on spontaneous sympathetic outflow and on sympathetic nerve and blood pressure responses to hypothalamic stimulation were examined in anesthetized cats in the present study. At a low dose (1 mg/kg) indoramin reduced blood pressure but did not significantly influence the level of efferent sympathetic nerve activity. A higher dose (5 mg/kg) lowered pressure further and inhibited activity in the splanchnic, cardiac and renal nerves indicating that reduced sympathetic outflow is a contributing factor to the hypotensive response at this dose. However, in contrast to other centrally acting antihypertensive agents, e.g., clonidine, indoramin did not inhibit the increase in sympathetic nerve activity produced by hypothalamic stimulation.