Effects of antagonists of 5-hydroxytryptamine on blood pressure in the anesthetised spontaneously hypertensive rat.
In pithed spontaneously hypertensive rats (SHR), the selective 5-HT2-receptor antagonist LY 53857 (1 mg/kg) had no effect on alpha 1- or alpha 2-adrenoceptors, but ketanserin (1 mg/kg) had some potency as an alpha 1-adrenoceptor antagonist, being approximately 100 times less potent than prazosin. Both ketanserin and LY 53857 (0.01 mg/kg) markedly antagonized the pressor response to 5-HT. In anesthetised SHR, both ketanserin and LY 53857 (1 mg/kg) significantly lowered diastolic blood pressure (DBP) alone or subsequent to administration of prazosin (1 mg/kg). In conscious SHR, LY 53857 (1 mg/kg) and ketanserin (0.1 mg/kg) did not significantly affect DBP, but ketanserin (1 mg/kg) significantly lowered DBP. It is concluded that ketanserin lowers DBP in conscious SHR mainly by alpha 1-adrenoceptor blockade, but that in anaesthetised SHR additional actions, possibly 5-HT2 blockade, contribute to the blood pressure lowering effects.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D003243:Consciousness; D004873:Ergolines / Q000494:pharmacology; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D051381:Rats; D011918:Rats, Inbred SHR; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects; D011985:Receptors, Serotonin / Q000187:drug effects; D012702:Serotonin Antagonists / Q000494:pharmacology*
D004873:Ergolines; D011942:Receptors, Adrenergic, alpha; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D007650:Ketanserin; C032663:LY 53857