[Difference in action sites between mecamylamine and hexamethonium on nicotinic receptors of sympathetic neurons].
To compare the difference in action sites between mecamylamine (MEC) and hexamethonium (HEX) on nicotinic receptors of sympathetic neurons, we investigated the effects of MEC and HEX on the nicotine-induced currents in cultured superior cervical ganglion neurons by whole-cell patch clamp technique. The IC(50) of MEC and HEX for antagonizing the effect of 0.08 mmol/L nicotine was 0.0012 and 0.0095 mmol/L, respectively. Both MEC and HEX accelerated the desensitization of nicotinic receptors. Furthermore, by comparing their effects at holding potentials 30, 70 and 110 mV, it was indicated that their suppressing effect on the nicotine-induced currents was voltage-dependent. However, different from that of HEX, the inhibitory effect of MEC increased with administering the mixture of MEC and nicotine at intervals of 3 min, indicating a use-dependent effect of MEC. It is concluded that the action site of MEC on nicotinic receptors of sympathetic neurons is different from that of HEX.
Liu
Wei
W
88 Hospital of Jinan Military Region, Taian 271000.
Zheng
Jian-Quan
JQ
Liu
Zhen-Wei
ZW
Li
Li-Jun
LJ
Wan
Qin
Q
Liu
Chuan-Gui
CG
D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D018738:Hexamethonium / Q000494:pharmacology*; D008464:Mecamylamine / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D011978:Receptors, Nicotinic / Q000187:drug effects* / Q000502:physiology; D017783:Superior Cervical Ganglion / Q000166:cytology / Q000502:physiology
D018733:Nicotinic Antagonists; D011978:Receptors, Nicotinic; D018738:Hexamethonium; D008464:Mecamylamine