“…Ketanserin, a potent and selective inhibitor of binding at the 5-HT2 site (Leysen et al, 1981), is also able to inhibit the vasoconstrictor effects of 5-HT in a variety of isolated tissues at low concentrations (Van Nueten et al, 1981b). In addition, the observation that ketanserin is able to lower blood pressure in experimental animals (Van Nueten et al, 1981a;Persson et al, 1982) and in man (De Cree et al, 1981;Wenting et al, 1982) has renewed interest in the involvement of 5-HT in hypertension. However, the mechanism ofthe hypotensive effect of ketanserin remains controversial since ketanserin also possesses appreciable a,-adrenoceptor antagonist activity and it appears that the acute administration of ketanserin in rats produces a hypotensive effect at doses similar to those required to block a,-adrenoceptors (Fozard, 1982;Kalkman etal., 1982).…”