Muscarinic agonists modulate calcium-dependent outward currents in an identified insect motoneurone.
The soma membrane of the fast coxal depressor (Df) motoneurone of the cockroach, Periplaneta americana possesses a population of acetylcholine receptors which respond to both nicotinic and muscarinic ligands. Activation of these 'mixed' acetylcholine receptors by McN-A-343 or oxotremorine results in the generation of an inward current at potentials positive to - 40 mV. A large proportion of the outward current induced by membrane depolarization in Df somata is due to a calcium-activated potassium conductance (IKCa) which shows a characteristic N-shape voltage-dependence. This N-shape of the membrane current-voltage relationship is suppressed by McN-A-343 or oxotremorine indicating that the agonist-induced inward current is due to a reduction in IKCa.
David
J A
JA
Gatty Marine Laboratory, School of Biological and Medical Sciences, University of St. Andrews, Fife, UK.
Pitman
R M
RM
D008455:(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethylammonium Chloride / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects; D009046:Motor Neurons / Q000502:physiology*; D018721:Muscarinic Agonists / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010526:Periplaneta; D015221:Potassium Channels / Q000502:physiology*
D018721:Muscarinic Agonists; D015221:Potassium Channels; D008455:(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethylammonium Chloride; D002118:Calcium