Inhibition of calcium influx in rabbit aorta by nicardipine hydrochloride (YC-93)

Relaxant actions of PGE2 and its derivative (YPG-209) on canine tracheal smooth muscle and their enhancement of Ca++ uptake by the microsomal fraction.

“…The addition of 15 mM lanthanum markedly reduced 45Ca uptake to a level of 40 nmol/g wet tissue in either H EPES-buffer A or B. As shown in Table 2, the increase in 45Ca influx by 83 mM KCI plus 20 mM tetraethylammonium (83 mM KCI plus 20 mM tetraethylammonium was used to produce a full depolarization) (8) was completely abolished by 10-5 M verapamil and inhibited by about 50% by 10'' M verapamil (data is not shown), whereas 45Ca uptake in the presence of 2.68 mM KCI was not significantly altered as reported with rabbit aorta (13,18). In were unable to affect significantly the cellular 45Ca uptake in either HEPES-buffer A or B.…”

“…of cellular 45Ca uptake: Celluar 45Ca uptake was determined by the lanthanum method (12) with some modi fication (13). Cleaned tracheal smooth muscle was cut transversely into blocks weighing about 50 mg.…”

Effects of nicardipine on the cross-perfused canine atrium.

“…In the present work, we demon strated that the effect of nicardipine on the frequency-force relationship was similar to effect of verapamil, indicating that nicardipine acts as a calcium antagonistic drug, as does verapamil or nifedipine. Terai et al (13) reported that nicardipine inhibited KCI induced 45Ca uptake in the rabbit aorta. From these results, it is concluded that nicardipine may produce predominantly cardiac depressant properties which are unrelated to phosphodiesterase inhibition.…”

A possible mechanism for relaxation of rat uterine smooth muscle by nicardipine hydrochloride (YC-93), a new potent vasodilator.

“…Our recent studies showed that nicardipine inhibits high K+-induced contraction of rabbit aortic smooth muscle with a concurrent inhibition of high K+ induced influx of calcium through the plasma membranes (30 …”