Effect of diltiazem on calcium- and noradrenaline-induced contractions in isolated rabbit aorta

The effect of diltiazem on calcium- and noradrenaline-induced contractions was investigated in the K-depolarized aortic strip of the rabbit. Diltiazem inhibited the contraction induced by calcium ions dose-dependently. A lower concentration of diltiazem produced no significant influence on the contraction induced by noradrenaline, while a higher concentration suppressed it. It is assumed that in the rabbit aorta diltiazem effectively inhibits the contraction mediated by the influx of calcium ions but it is less effective with the contraction induced by the release of sequestered calcium.