No evidence for the involvement of histamine (H 1 or H 2) receptors in the hypotension and presynaptic inhibition of sympathetic nerve function caused by LY-141865 in dogs

Abstract

LY-141865, a partial ergoline, caused hypotension, bradycardia and significant impairment of cardioacceleration elicited during stimulation of cardiac sympathetic nerves. These cardiovascular actions of LY-141865 were not affected either by the H 1-receptor antagonist mepyramine or the H 2-receptor antagonist cimetidine. The dopamine receptor antagonist sulpiride significantly reduced the hypotensive, bradycardic and presynaptic inhibitory actions of LY-141865. These results show that while dopamine receptor activation is responsible for the hypotension and presynaptic inhibition of sympathetic nerve function caused by LY-141865, histamine (H 1- or H 2-) receptors do not play any role in these actions of the compound.