Effects of m-nisoldipine and nisoldipine on isolated uterine muscle

m-Nisoldipine (m-Nis) and nisoldipine (Nis) inhibited spontaneous contraction of isolated non-pregnant human myometrium, IC50 being 3.7 +/- 0.7 mumol.L-1 for m-Nis and 6.0 +/- 0.9 mumol.L-1 for Nis. Both drugs also suppressed spontaneous and oxytocin-induced contraction of isolated pregnant rat uterus. In isolated uterus from virgin rat, both drugs inhibited the contractions induced by KCl, acetylcholine (ACh), and oxytocin (Oxy), the values of pD'2 against KCl, ACh, Oxy being 9.0 +/- 0.2, 6.1 +/- 0.1, and 5.9 +/- 0.1 for m-Nis and 9.1 +/- 0.3, 5.7 +/- 0.2, and 5.6 +/- 0.1 for Nis respectively. The results indicate that both m-Nis and Nis may be clinically useful for the treatment of dysmenorrhea and premature labour.