Chronic 5-HT2 receptor blockade with ritanserin does not reduce blood pressure in the spontaneously hypertensive rat.

Chronic oral treatment (8 weeks) with the selective 5-hydroxytryptamine2 (5-HT2)-receptor blocking agent, ritanserin, did not reduce blood pressure in the spontaneously hypertensive rat (SHR) during basal conditions or during stress (jet air). In pithed rats the pressor responses to 5-HT but not to phenylephrine or sympathetic stimulation of the sympathetic outflow were completely antagonized. These observations indirectly suggests that the 5-HT2-receptor blocking properties of the antihypertensive agent ketanserin cannot alone account for the antihypertensive effects in SHR that are observed during chronic treatment with this agent.