Excitation-contraction coupling in the heart.

There has been dramatic progress in our understanding of normal cardiac excitation-contraction coupling and in control of contraction strength, as the result of the new patch pipette method of voltage clamping of single cells and the new methods for monitoring Cai. Several abnormalities have been shown to exist in hypertrophied muscle; the action potential is changed and the contraction is slower. A kinetic change appears to exist in the L-type Ca current, associated with a slower decay of Cai. The next few years should bring a much improved understanding of the molecular and cellular basis for the changes of hypertrophy.