Post-tetanic potentiation is due to -
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."
Hyperpolarization of muscle fibres
Rapid K+ efflux
Increased availability of Ca++
Rapid Na+ influx