The cardiovascular effects of
OPC-13340, a newly developed
1,4-dihydropyridine calcium channel blocker, were examined in several canine preparations. In conscious normotensive and
DOCA-
salt hypertensive dogs,
OPC-13340, at doses of 10 to 30 micrograms/kg, i.v., and 0.3 to 3 mg/kg, p.o., exerted an hypotensive action in a dose-dependent manner. The hypotensive action of
OPC-13340 was longer lasting and more potent than that of
nicardipine and
nifedipine. In conscious, normotensive instrumented dogs,
OPC-13340, at doses of 1 and 3 mg/kg, p.o., dose-dependently decreased total peripheral resistance and mean blood pressure and increased heart rate, cardiac output and left ventricular contractility. In anesthetized open-chest dogs,
OPC-13340, at doses of 1 to 30 micrograms/kg, i.v., increased coronary blood flow and decreased mean blood pressure, heart rate, coronary vascular resistance, arteriovenous
oxygen difference and myocardial oxygen consumption. In contrast to
OPC-13340,
nicardipine did not change the myocardial oxygen consumption. From these results it was concluded that
OPC-13340 lowered blood pressure and improved coronary circulation in dogs and that the duration of these actions was longer lasting than that of
nifedipine and
nicardipine. These actions of
OPC-13340 may be useful in the treatment of
hypertension and
angina pectoris.