Role of External Calcium and Sarcolemmal Na/Ca Exchange in the Depolarisation-Contraction Coupling in Mammalian Skeletal Muscle

In normal or denervated soleus muscle, all manoeuvres (changes in [Na]o or addition of PXB, PLD) which are known to affect the proportion of the rapidly exchangeable Ca bound to the sarcolemma and related to Na-Ca exchange, induce concommitant changes in the d-c coupling.