No evidence for the involvement of histamine (H1 or H2) receptors in the hypotension and presynaptic inhibition of sympathetic nerve function caused by LY-141865 in dogs.
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 H1-receptor antagonist mepyramine or the H2-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 (H1- or H2-) receptors do not play any role in these actions of the compound.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D004285:Dogs; D004873:Ergolines / Q000494:pharmacology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D019257:Quinpirole; D011954:Receptors, Dopamine / Q000502:physiology; D011968:Receptors, Histamine / Q000502:physiology*; D011969:Receptors, Histamine H1 / Q000502:physiology*; D011970:Receptors, Histamine H2 / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000187:drug effects*
D004873:Ergolines; D011954:Receptors, Dopamine; D011968:Receptors, Histamine; D011969:Receptors, Histamine H1; D011970:Receptors, Histamine H2; D019257:Quinpirole