Post-tetanic potentiation is due to -: (A) Hyperpolarization of muscle fibres, (B) Rapid K+ efflux, (C) Increased availability of Ca++, (D) Rapid Na+ influx
Answer is C. Ans. is 'c' i.e., Increased availability of Ca++ "Repetitive stimulation enhances force development due to rise in intracellular Ca++, a phenomenon called posttetanic potentiation. It is due to increased phosphorylation of myosine light chain with increased number of cross bridges."