Salt and the action of calcium antagonists.

Calcium antagonists are unique in that they combine vasodilating and natriuretic properties. Although the acute natriuretic response, and details on intrarenal mechanisms of action, have been documented in the past, recent evidence shows intrarenal actions even in the chronic steady state of antihypertensive medication. Chance observations led to recent systematic studies that clearly document (a) that the antihypertensive action of calcium antagonists is not antagonized by high sodium diet and (b) that there is negative interaction between diuretics and calcium antagonists with respect to their antihypertensive actions. Potential mechanisms for the salt/diuretic-calcium antagonist interactions include (i) intrinsic natriuretic property of calcium antagonists, (ii) interaction of volume control and hormonal calcium control systems, and (iii) modulation of--at least dihydropyridine--binding sites by dietary sodium.