Problems in Calcium Exchange

Abstract

A number of projects, the solutions of which would greatly advance present concepts of transcellular Ca movement, were discussed:

• 1. Identification, at the molecular level, of the Ca binding sites within the sarcolemmal membrane. The anionic phospholipids seem to be the prime candidates.

• 2. Localization of the binding sites vis-a-vis inner or outer portion of the sarcolemma.

• 3. Development of specific probes for the anionic phospholipids so that phospholipid-Ca interaction can be correlated with contractile function in the whole cell.

• 4. The role of membrane fluidity in the determination of Ca movements. For example, the effect of alteration of cholestrerol/ phospholipid ratio.

• 5. Development of realistic physical concepts for control of movement of Ca from binding sites to transmembranous channels or carriers.

• 6. Establishment of the discrete points of action of various excitation-contraction uncouplers, e.g., cations, calcium blocking drugs.