Influence of apomorphine on sympathetic neural transmission in the nictitating membrane of the cat.
Apomorphine inhibited the nictitating membrane contractions elicited by pre- or postganglionic stimulation of the cervical sympathetic nerve but did not influence even in higher doses the effect of noradrenaline and adrenaline on this organ. The inhibition evoked by apomorphine could be antagonized by haloperidol but was not influenced by phentolamine and propranolol. Dopamine and noradrenaline inhibited the nictitating membrane contractions elicited by nerve stimulation, but clonidine was ineffective in our experiments. Haloperidol antagonized the inhibition evoked by dopamine but did not influence the similar effect of noradrenaline.
D000818:Animals; D001058:Apomorphine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002415:Cats; D003000:Clonidine / Q000494:pharmacology; D004298:Dopamine / Q000494:pharmacology; D006220:Haloperidol / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009433:Neural Inhibition; D009541:Nictitating Membrane / Q000187:drug effects* / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D011941:Receptors, Adrenergic / Q000187:drug effects; D013564:Sympathetic Nervous System / Q000187:drug effects*; D009435:Synaptic Transmission / Q000187:drug effects*
D011941:Receptors, Adrenergic; D006220:Haloperidol; D003000:Clonidine; D001058:Apomorphine; D004298:Dopamine; D009638:Norepinephrine; D010646:Phentolamine