The effect of insulin on plasma-membrane and mitochondrial-membrane potentials in isolated fat-cells.
1. A recently developed technique for the measurement of plasma-membrane and mitochondrial-membrane potentials in intact cells by using the distribution of 86Rb+ and [3H]methyltriphenylphosphonium+ has enabled us to characterize a novel insulin effect on fat-cell mitochondria. For control cells the plasma-membrane and mitochondrial-membrane potentials were 75 mV and 152 mV respectively. Insulin (10 mu units/ml) caused a 9 mV hyperpolarization of the plasma membrane and a 19 mV depolarization of the mitochondrial membrane. 2. The insulin-dependent mitochondrial depolarization was observed at physiological insulin concentrations (10 mu units/ml) and was apparent when the cells metabolized a wide variety of substrates. 3. Evidence from the uptake of the weak acid 5,5-dimethyloxazolidine-2,4-dione by fat-cells was interpreted as indicating that the mitochondrial pH gradient was increased by insulin. 4. Insulin alters the balance between the electrical and pH-gradient components that form the mitochondrial protonmotive force. A model is proposed.
D000273:Adipose Tissue / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects; D004114:Dimethadione / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D007425:Intracellular Membranes / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects*; D008954:Models, Biological; D009861:Onium Compounds / Q000378:metabolism; D051381:Rats; D012413:Rubidium / Q000378:metabolism; D014320:Triphenylmethyl Compounds / Q000378:metabolism
D007328:Insulin; D009861:Onium Compounds; D014320:Triphenylmethyl Compounds; C011561:triphenylmethylphosphonium; D004114:Dimethadione; D012413:Rubidium