OSCILLATIONS OF MEMBRANE CURRENT AND EXCITABILITY DRIVEN BY METABOLICOSCILLATIONS IN HEART-CELLS

Periodic changes in membrane ionic current linked to intrinsic oscilla tions of energy metabolism were identified in guinea pig cardiomyocyte s. Metabolic stress initiated cyclical activation of adenosine triphos phate-sensitive potassium current and concomitant suppression of depol arization-evoked intracellular calcium transients. The oscillations in membrane current and excitation-contraction coupling were linked to o scillations in the oxidation state of pyridine nucleotides but were no t driven by pacemaker currents or alterations in the concentration of cytosolic calcium. Interventions that altered the rate of glucose meta bolism modulated the oscillations, suggesting that the rhythms origina ted at the level of glycolysis. The energy-driven oscillations in pota ssium currents produced cyclical changes in the cardiac action potenti al and thus may contribute to the genesis of arrhythmias during metabo lic compromise.