Inhibition of Na/Ca exchange by Phe-Met-Arg-Phe-NH2 (FMRFa)-related peptides in intact rat pancreatic B-cells.
Phe-Met-Arg-Phe-NH2 (FMRFa)-related peptides were recently shown to inhibit Na/Ca exchange in cardiac sarcolemmal vesicles. In the present study, we examined the effects of FMRFa-related peptides on Na/Ca exchange in intact (pancreatic B) cells. At 2.8 mM glucose, FMRFa-related peptides only weakly inhibited Na/Ca exchange although their effect was more marked under depolarizing conditions. The peptides blocked neither the Na/K-ATPase nor Ca2+ channels but slightly reduced membrane K+ permeability. Our data indicate that FMRFa-related peptides are weak and non-specific inhibitors of Na/Ca exchange in intact B cells. The data do not confirm the view that the peptides may exert some of their physiological modulatory role by inhibiting Na/Ca exchange.
Van Eylen
F
F
Laboratory of Pharmacology, Brussels University School of Medicine, Belgium.
Gourlet
P
P
Vandermeers
A
A
Lebrun
P
P
Herchuelz
A
A
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D002352:Carrier Proteins / Q000037:antagonists & inhibitors*; D002463:Cell Membrane Permeability / Q000187:drug effects; D019835:FMRFamide; D005947:Glucose / Q000494:pharmacology; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects; D009479:Neuropeptides / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism; D051381:Rats; D019831:Sodium-Calcium Exchanger; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D015220:Calcium Channels; D002352:Carrier Proteins; D009479:Neuropeptides; D019831:Sodium-Calcium Exchanger; D013757:Tetraethylammonium Compounds; D019835:FMRFamide; D019789:Tetraethylammonium; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000254:Sodium-Potassium-Exchanging ATPase; D005947:Glucose; D011188:Potassium