Ketanserin

Ketanserin causes a dose-dependent inhibition on the contractile responses to 5-hydroxytryptamine of isolated rat caudal artery, canine basilar, carotid, coronary and gastrosplenic arteries, canine gastrosplenic veins and canine saphenous veins. Ketanserin inhibits the contractions of rat caudal arteries and canine saphenous veins caused by postjunctional alpha adrenergic activation. Ketanserin depresses and in certain experiments reverses the vasoconstrictor response to 5-hydroxytryptamine in the perfused guinea-pig stomach. ^[1] Ketanserin is found to attenuate the excitatory responses produced by norepinephrine, an alpha 1-adrenoceptor-mediated response, in the lateral geniculate nucleus. Ketanserin potentiates rather than attenuates, the inhibitory effect of 5-HT in the lateral geniculate nucleus. ^[2] Ketanserin significantly prolongs action potential duration (APD) at 50% repolarization by 218% and APD at 90% repolarization by 256% with no significant effect on other action potential parameters in rat ventricular myocytes. Ketanserin results in a concentration- and time-dependent inhibition of charge area of Ito evaluated by integration with an EC50 of 8.3 μM. Ketanserin also blocks Ito and sustained current (ISus) in a dose-dependent manner with an EC50 of 11.2 μM and has no significant effect on both the inward rectifier potassium current and the L-type calcium current. ^[3]

Ketanserin produces dose-dependent antinociception in the hot-plate and acetic acid-induced writhing tests with ED50 values (95% confidence limit) of 1.51 and 0.62 mg/kg, respectively, but is without any significant effect on the tail-flick test. ^[4]