[The effects of ketanserin on the hemodynamic response after intracerebroventricular administration of 5-hydroxytryptamine].

Recently, the serotonergic nervous system has been receiving attention, as it participates in the hemodynamic regulation as well as in the pathogenesis of hypertension. The purpose of this experiment is to investigate the role of the central and peripheral serotonergic receptor in the hemodynamic responses induced by intracerebroventricular (i.c.v) administration of 5-hydroxytryptamine (5-HT). Eight week-old male spontaneously hypertensive rats (SHR) and age matched Wistar Kyoto rats (WKY) were used, and the experiment was performed under conscious and minimum restrained states. Five micrograms of 5-HT was given i.c.v. followed by i.c.v. administration of 200 micrograms ketanserin. Mean arterial pressure (MAP) and heart rate (HR) were observed continuously for 30 minutes. Then 5 micrograms of 5-HT was given i.c.v. again in the same rat (SHR -IC group, n = 7; WKY-IC group, n = 7). The rest of the rats received 200 micrograms of ketanserin intravenously (i.v.) after i.c.v. administration of 5 micrograms 5-HT, and the same amount of 5-HT was given i.c.v. after the ketanserin i.v. (SHR-IV group, n = 7; WKY-IV group, n = 6). Five-HT elicited a significant pressor response in all groups of rats and a slight non-significant increase in HR. In SHR-IC group and WKY-IC group, neither ketanserin i.c.v. nor the second 5-HT i.c.v. administration caused significant changes in MAP and HR. In SHR -IV group, i.v. ketanserin caused a significant decrease in MAP (-8.8 +/- 1.4 mmHg), but no significant change in MAP in WKY-IV group (-1.1 +/- 1.2 mmHg).(ABSTRACT TRUNCATED AT 250 WORDS)