Impaired vasodilator and chronotropic responses to 5-hydroxytryptamine in two models of hypertension-associated cardiac hypertrophy.
OBJECTIVE
In connection with hypertension, research concerning 5-hydroxytryptamine (5-HT) receptors and subtypes in the cardiovascular system has so far been predominantly focused on various vascular tissues. In this study, the effects of 5-HT were investigated in isolated hearts with experimental cardiac hypertrophy.


METHODS
Cardiac hypertrophy was induced by stenosing the abdominal aorta (ASR) of 5-week-old Wistar rats. The functional response to serotonin was measured in unpaced, ASR hearts (18-20 weeks) and compared with those of "sham" operated SHR and WKY rats.


RESULTS
The ASR, less hypertensive than SHR, showed more pronounced cardiac hypertrophy. The positive chronotropic and coronary vasodilator response to 5-HT was reduced in hypertrophied hearts from SHR and ASR when compared to "sham" operated and normotensive controls. The positive chronotropic effect of 5-HT could be antagonised with ketanserin, without affecting the coronary vasodilation. 5-HT did not induce any change in contractile force.


CONCLUSIONS
Cardiac hypertrophy is associated with impaired coronary vasodilator and chronotropic responsiveness to serotonin. The chronotropic response to 5-HT is mediated by the 5-HT2-receptor subtype.
Department of Pharmacotherapy, Academic Medical Centre, Amsterdam, The Netherlands.
M J
MJ
Mertens
M
M
Pfaffendorf
P A
PA
van Zwieten
D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D006332:Cardiomegaly / Q000209:etiology / Q000503:physiopathology*; D004195:Disease Models, Animal; D006339:Heart Rate / Q000502:physiology*; D006973:Hypertension / Q000150:complications / Q000503:physiopathology*; D008297:Male; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012701:Serotonin / Q000502:physiology*; D014664:Vasodilation / Q000502:physiology*
D012701:Serotonin