Cardiac Ca2+ signaling

The molecular mechanisms that control the processes of E-C coupling in heart muscle have evolved along different evolutionary paths than those of skeletal muscle. In skeletal muscle, while voltage has evolved as the dominant signal for gating of Ca2+ release, calcium has taken the primary signaling role in the heart muscle. Anatomical and functional constraints on the two muscle types may have brought about such a mechanistic differentiation. Although it is by no means clear that the two signaling paths are mutually exclusive, the dominance of each signaling mechanism, in their respective tissues, was recognized around the turn of the century. It is now generally accepted that Ca2+ signaling occurs not on a global cytosolic level but primarily in micro-domains surrounding the DHP/RyRs. How molecularly the two proteins cross-talk, is the subject of this chapter.