J Korean Neurosurg Soc.  1994 Nov;23(11):1234-1243.

Studies on the Interactions of M1-, M2- Receptors with Nicotinic Receptors in Rabbit Sympathetic Ganglia

• Ryu CS
• Kang SS
• Lee JH
• Kim JK

Abstract

Effects of a M1 receptor antagonist, pirenzepine, a M2 receptor antagonist, AF-DX116, and a nicotinic receptor antagonist, mecamylamine on the pressor responses to preganglionic sympathetic nerve stimulation(PNS) and McN-A-343 and DMPP in spinal(pithed) rabbits were investigated in order to elucidate a functional role of M1, M2 and nicotinic receptors in ganglionic transmission. Pirenzepine and AF-DX116 selectively inhibited the McN-A-343-induced pressor reponse in chlorisondamine-treated rabbit and the BCh-induced bradycardia, respectively. Electrical stimulations of preganglionic sympathetic outflow at T8 level produced increases in blood pressure. Pirenzepine(3 microgram/kg) significantly inhibited the PNS-induced pressor response and the degree of inhibition was not changed by increasing the doses to 100 microgram/kg. AF-DX116(100 microgram/kg) had no effect on the PNS-induced pressor response. Mecamylamine inhibited the PNS-induced pressor response in a dose-dependent manner. The inhibitory action of mecamylamine was significantly augmented by combined-treatment with pirenzepine(30 microgram/kg) but AF-DX116(100 microgram/kg) did not affect the inhibitory action of mecamylamine. McN-A-343 and DMPP elicited pressor response in the spinal rabbit. Pirenzepine and AF-DX116 dose-dependently inhibited the McN-A-343-induced pressor response but they did not affect DMPP-induced pressor response. Mecamylamine inhibited both pressor responses induced by Mc-N-343- and DMPP. These results suggest that not only nicotinic receptors but also M1 receptors play a facilitatory role in ganglionic transmission but M2 receptors do not contribute the transmission in spinal(pithed) rabbits.

Keyword

Experiment; Sympathetic ganglia; Muscarinic; Nicotinic receptor antagonist; Agonist

MeSH Terms

(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethylammonium Chloride
Blood Pressure
Bradycardia
Dimethylphenylpiperazinium Iodide
Electric Stimulation
Ganglia, Sympathetic*
Ganglion Cysts
Mecamylamine
Pirenzepine
Rabbits
Receptors, Nicotinic*
(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethylammonium Chloride
Dimethylphenylpiperazinium Iodide
Mecamylamine
Pirenzepine
Receptors, Nicotinic