A cascade of events (signal-transduction), mainly seen in rat cardiac myocytes and renal cells, is thought to occur after ouabain interaction with a minor fraction of Na + /K + -ATPase. Ahigher intracellularNa + concentration followed sodium pump inhibition by ouabain with a subsequent gradual increase or oscillations in intracellular Ca 2+ con-centration. Whether this increase in intracellular Ca 2+ concentration is part of the cascade, a result of the cascadeor a totally independent phenomenon are conflicting interpre-tations that are discussed. .
