Insulin-induced hyperpolarization in mammalian skeletal muscle

S. T. Iannaccone, K. X. Li, N. Sperelakis, D. A. Lathrop

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Insulin-induced hyperpolarization of up to 9 mV has been described in isolated frog [J. Physiol. Lond. 252: 43-58, 1975; Am. J. Physiol. 251 (Cell Physiol. 4): C249-C254, 1979] and mammalian (Molecular Basis of Insulin Action, New York: Plenum, 1985, p. 451-463; Am. J. Physiol. 197: 524-526, 1959; Am. J. Physiol. 198: 1066-1070, 1960) skeletal muscle. We have shown that a similar hyperpolarization occurs in situ after administration of insulin in anesthetized rats. In streptozotocin (STZ)-treated rats, insulin produced ~66-70% of the hyperpolarization observed in normal rat skeletal muscle in situ. Administration of ouabain in situ blocked the insulin-induced hyperpolarization in the normal group of rats and significantly blunted the effect in the STZ group. These results suggest that insulin-induced hyperpolarization in skeletal muscle results from direct activation of the Na+-K+-ATPase pump. In isolated skeletal muscle from normal and STZ rats, there was no difference in the amount of the insulin-induced hyperpolarization. There was an additive, but small, hyperpolarizing effect of insulin and isoproterenol when administered in combination, suggesting that the greater magnitude of the insulin-induced hyperpolarization observed in situ in normal rats may be due to an additive effect of injected insulin and endogenous release of epinephrine. Alternatively, STZ treatment may directly alter the Na+-K+ pump so that its response to insulin is lessened.

Original languageEnglish (US)
Pages (from-to)25/2
JournalAmerican Journal of Physiology - Cell Physiology
Volume256
Issue number2
StatePublished - Jan 1 1989

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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