Cardiovascular action of m-nisoldipine in anaesthetized rabbits and guinea pigs

In anaesthetized rabbits, the effects of iv m-nisoldipine (m-Nis) or nisoldipine (Nis) 10 vg/kg with respect to decreasing blood pressure were equally potent, however, the depression of heart contractility induced by m-Nis was weaker than that by Nis. Diastolic blood pressure began to fall 20 min after m-Nis 90 vg/kg was administered intraduodenally, with the depressing effect being longer than 2h. In vitro m-Nis inhibited KCl-induced contraction of the rabbit aortic strips, and the activity was not affected by exposing the drug to light for 24 h. m-Nis failed to affect noradrenaline-induced contractions of the same preparation. m-Nis l, 5 yg increased the coronary blood flow significantly in guinea pig Langendorff heart preparations, while bheart contractility was slightly depressed.