Activation of muscarinic receptors increases the concentration of free Na+ in mouse pancreatic B-cells.
The fluorescent probe SBFI was used to monitor the influence of acetylcholine (ACh) on the cytosolic concentration of free Na+ (Na+i) in single mouse pancreatic B-cells. In the presence of 3 mM glucose and 135 mM extracellular Na+, Na+i averaged 16.6 mM. ACh (100 microM) increased Na+i by approximately 80%. This rise was prevented by atropine, a blocker of muscarinic receptors, and by omission of extracellular Na+, but still occurred if the sodium pump was blocked by ouabain. It was unaffected by tetrodotoxin, a blocker of voltage-sensitive Na+ channels, and was not mimicked by depolarization of the cells with high K+. It is concluded that activation of muscarinic receptors increases the membrane permeability to Na+ in pancreatic B-cells.
Gilon
P
P
Unité d'Endocrinologie et Métabolisme, UCL 55.30, University of Louvain Faculty of Medicine, Brussels, Belgium.
Henquin
J C
JC
D000818:Animals; D005260:Female; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D011976:Receptors, Muscarinic / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism; D013779:Tetrodotoxin / Q000494:pharmacology
D011976:Receptors, Muscarinic; D015222:Sodium Channels; D013779:Tetrodotoxin; D012964:Sodium