Membrane potentials in cell-free preparations from guinea pig cerebral cortex: effect of depolarizing agents and cyclic nucleotides.
The distribution of [3H]triphenylmethylphosphonium ion between the medium and vesicular entities was examined in a cell-free, particulate preparation from guinea pig cerebral cortex. This distribution followed the Nernst relationship with regard to the external potassium ion concentration and, in physiological media, indicated the maintenance of a mean trans-membrane potential ranging from -58 to -78 mV. The neurotoxins batrachotoxin, veratridine, and grayanotoxin I, partially depolarized the preparation. Tetrodotoxin blocked the depolarization by batrachotoxin, veratridine, and gray-anotoxin I. The depolarization by these neurotoxins was potentiated by the presence of anemone toxin II and presumably reflected the response of vesicular components of neuronal origin. An additional potassium-sensitive depolarization probably represented the response of vesicular components of glial origin with an apparent transmembrane potential of -8 to -35 mV. No correlation could be demonstrated between changes in transmembrane potential and stimulation of cyclic AMP generation by a variety of agents in this preparation.
D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology*; D000242:Cyclic AMP / Q000378:metabolism; D006168:Guinea Pigs; D007700:Kinetics; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D009861:Onium Compounds / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology; D014118:Toxins, Biological / Q000494:pharmacology*; D014320:Triphenylmethyl Compounds / Q000378:metabolism
D018377:Neurotransmitter Agents; D009861:Onium Compounds; D014118:Toxins, Biological; D014320:Triphenylmethyl Compounds; C011561:triphenylmethylphosphonium; D000242:Cyclic AMP; D011188:Potassium