Role of protein kinase C in insulin activation of the Na-K pump in cultured skeletal muscle

S. R. Sampson, C. Brodie, S. V. Alboim

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Administration of insulin to preparations of skeletal muscle causes an increase in Na+-K+ pump activity within 15-30 min. Although several mechanisms have been proposed, such as promotion of Na+ influx and translocation of pumps from intracellular to membrane sites, the early events involved in this effect remain unknown. We have investigated the possibility that activation of protein kinase C (PKC) may be an initial event in Na+- K+ pump activation in primary cultures of rat skeletal muscle. Insulin (80- 100 mU/ml) and tumor-promoting phorbol esters (10-100 nM) increased Na+-K+ pump activity as determined by measurements of ouabain-suppressible 86Rb uptake, electrogenic pump component of membrane potential, and specific [3H]ouabain binding. These effects were not reduced by treatment of myotubes with amiloride, which blocks Na+-H+ exchange, or with tetrodotoxin, which blocks voltage-dependent Na+ channels. Effects of insulin and phorbol esters were not additive, suggestive of a common mechanism. Effects of both phorbol esters and insulin were significantly reduced by staurosporine (50-100 nM) and by downregulation of PKC (by pretreatment of myotubes with phorbol ester for 24 h). The findings suggest that insulin may stimulate Na+-K+ pump activity in skeletal muscle by activation of PKC.

Original languageEnglish
Pages (from-to)C751-C758
JournalAmerican Journal of Physiology - Cell Physiology
Issue number3 35-3
StatePublished - 1994


  • amiloride
  • membrane potential
  • ouabain
  • phorbol esters


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