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Journal of Korean Neurosurgical Society 1994;23(11): 1234-1243. |
| Studies on the Interactions of M1-, M2- Receptors with Nicotinic Receptors in Rabbit Sympathetic Ganglia. |
| Chun Sik Ryu, Sam Suk Kang, Je Hyuk Lee, Jong Keun Kim |
1Department of Neurosurgery, Chonnam University Medical School, Kwangju, Korea.
2Department of Pathology, Chonnam University Medical School, Kwangju, Korea. |
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| ABSTRACT |
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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. |
| Key Words:
Experiment; Sympathetic ganglia; Muscarinic; Nicotinic receptor antagonist; Agonist |
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