Effects of a novel dihydropyridine calcium antagonist on venous capacitance in Wistar-Kyoto rats.

Calcium antagonists are potent dilators of resistance vessels but do not dilate capacitance vessels. CD832 is a novel dihydropyridine calcium antagonist which has a nitrate moiety in its chemical structure. The authors examined the effects of CD832 on venous capacitance in anaesthetized rats. Venous capacitance was assessed by measuring mean circulatory filling pressure (MCFP) at three levels of blood volume. Nitroglycerin decreased and phenylephrine increased MCFP. CD832 did not alter MCFP. After treatment with hexamethonium to prevent reflex venoconstriction, CD832 significantly decreased MCFP but nicardipine (another dihydropyridine calcium antagonist) did not. The magnitude of hypotension caused by CD832 and nicardipine was comparable