Effects of N-methyl- and N-isobutyl-1,2-diphenyl ethanol amines on the spontaneous and evoked contractions in the rat isolated uterus.

1. The effects of N-methyl- and N-isobutyl-1,2-diphenyl ethanol amine (compounds M & E), respectively and diltiazem (D) were examined on the spontaneous and evoked uterine contractions of pregnant rats in vitro. 2. Addition of compound M (75-300 microM), compound E (15-60 microM) or D (100-400 nM) to the uterine tissues, inhibited the spontaneous contractions in a dose-dependent manner. The potency order was D greater than E greater than M. 3. The inhibitions were reversed by elevating the extracellular Ca2+ concentration by 20 mM. The compounds also antagonised CaCl2-evoked contractions. 4. Treatment of rats with either compound during pregnancy days (1-16) did not affect the implantation process and did not induce any teratogenicity. 5. The uterine inhibitory effects of the compounds may be due to blockade of uterine Ca2+ channels.