Faculty Collaboration Database

Nicotine-induced depolarization of cerebral cortical synaptosomes is dependent upon sodium. Neuropharmacology 1992 Sep;31(9):909-14

Date

09/01/1992

Pubmed ID

1436397

DOI

10.1016/0028-3908(92)90129-d

Scopus ID

2-s2.0-0026649252 (requires institutional sign-in at Scopus site)   4 Citations

Abstract

Earlier studies from this laboratory demonstrated that activation of nicotinic cholinergic receptors of cerebral cortical synaptosomes of the rat produced a decrease in the accumulation of [3H]tetraphenylphosphonium ([3H]TPP+) as a result of a decreased synaptosomal membrane potential. In the present study, the role of sodium in the effect of nicotine on the accumulation of [3H]TPP+ and the estimated potential difference was explored. Replacement of buffer sodium with either sucrose or N-methyl-D-glucamine (NMDG), attenuated the depolarization produced by the sodium channel activator, veratridine and had no effect on potassium-induced depolarization. The effect of nicotine on accumulation of [3H]TPP+ into cerebral cortical synaptosomes was abolished in sucrose buffer and attenuated in NMDG buffer. 1,1-Dimethyl-4-phenylpiperazinium iodide (DMP; 30 microM) produced a small increase in the influx of 22Na+ into cerebral cortical synaptosomes. The effect of DMPP on the influx of 22 Na+ was not blocked by tetrodotoxin. These results support the hypothesis that the nicotinic cholinergic receptor in the brain, functions as a sodium ionophore and further demonstrate that accumulation of synaptosomal [3H]TPP+ provides a simple tool with which to assess the effect of nicotine on sodium permeability through open nicotinic cholinergic receptor ionophores.

Author List

Hillard CJ

Author

Cecilia J. Hillard PhD Associate Dean, Center Director, Professor in the Pharmacology and Toxicology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Antineoplastic Agents
Cerebral Cortex
Dimethylphenylpiperazinium Iodide
In Vitro Techniques
Male
Membrane Potentials
Neuromuscular Depolarizing Agents
Nicotine
Onium Compounds
Organophosphorus Compounds
Potassium
Rats
Rats, Sprague-Dawley
Receptors, Cholinergic
Sodium
Sodium Radioisotopes
Synaptosomes
Veratridine