Abstract
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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / pharmacology
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Animals
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Calcium Channels / drug effects
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Calcium Channels / metabolism
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Carrier Proteins / antagonists & inhibitors*
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Cell Membrane Permeability / drug effects
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FMRFamide
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Glucose / pharmacology
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Islets of Langerhans / drug effects
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Islets of Langerhans / metabolism*
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Membrane Potentials / drug effects
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Neuropeptides / pharmacology*
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Potassium / metabolism
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Rats
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Sodium-Calcium Exchanger
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Sodium-Potassium-Exchanging ATPase / antagonists & inhibitors
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Tetraethylammonium
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Tetraethylammonium Compounds / pharmacology
Substances
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Calcium Channels
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Carrier Proteins
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Neuropeptides
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Sodium-Calcium Exchanger
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Tetraethylammonium Compounds
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FMRFamide
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Tetraethylammonium
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3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester
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Sodium-Potassium-Exchanging ATPase
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Glucose
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Potassium