EFFECTS OF A NOVEL DIHYDROPYRIDINE CALCIUM-ANTAGONIST ON VENOUS CAPACITANCE IN WISTAR-KYOTO RATS

Calcium antagonists are potent dilators of resistance vessels but do n ot dilate capacitance vessels. CD832 is a novel dihydropyridine calciu m antagonist which has a nitrate moiety in its chemical structure. The authors examined the effects of CD832 on venous capacitance in anaest hetized rats. Venous capacitance was assessed by measuring mean circul atory filling pressure (MCFP) at three levels of blood volume. Nitrogl ycerin decreased and phenylephrine increased MCFP. CD832 did not alter MCFP. After treatment with hexamethonium to prevent reflex venoconstr iction, CD832 significantly decreased MCFP but nicardipine (another di hydropyridine calcium antagonist) did not. The magnitude of hypotensio n caused by CD832 and nicardipine was comparable. The results suggest that CD832 is a unique calcium antagonist which has a venodilator effe ct.