[Nicotinic currents of cultured rat superior cervical ganglion neurons and use-dependent block by mecamylamine].

AIM: Comparison of action of nicotinic agonists and antagonists on nicotinic acetylcholine receptor (nAChR) in superior cervical ganglion (SCG) neurons.

METHODS

Whole-cell recordings were made from cultured neonatal rat SCG neurons. Cholinergic drugs were applied by local pressure perfusion.

RESULTS

The neurons were activated by nicotinic agonists and peak current were acetylcholine (ACh), 443 +/- 183 pA; nicotine, 1175 +/- 377 pA; dimethylphenylpiperazinium (DMPP), 2946 +/- 358 pA, respectively. The nicotinic responses were blocked by mecamylamine (Mec), hexamethonium and curare, the efficacies were 435 +/- 154 pA, 725 +/- 320 pA, 887 +/- 214 pA, but not by alpha-bungarotoxin. The block by Mec was use-dependent, i.e., it was dependent on repeated presentation of the agonists. The first 6 peak currents were expressed as percentage of the first response as following: 100, 64 +/- 3, 50 +/- 3, 41 +/- 4, 32 +/- 3%.

CONCLUSION

The present data suggest that nAChR of SCG neurons have different pharmacological characteristics from that of muscle or central neurons.