Clinical endocrinology · 1997
Anisomycin and verapamil influence the action of progesterone on regulation of term human myometrial contractile activity.
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Fu X, Moberg C, Bäckström T, Ulmsten U, Gylfe E
Аннотация
OBJECTIVE: Progesterone has been shown to have both stimulatory and inhibitory effects on term human myometrial contractile activity. The mechanisms involved in this action of progesterone are still poorly understood.
DESIGN: Myometrial tissues were obtained from the lower uterine segment at elective Caesarean section of 30 term pregnant women. The contractile activity of muscle strips was measured by a superfusion technique and protein synthesis evaluated by [3H]-leucine incorporation.
RESULTS: [3H]-leucine incorporation into term myometrial strips was not affected by progesterone (10 mumol/l), but was markedly reduced by the protein synthesis inhibitor anisomycin (P < 0.05). However, progesterone increased frequency and tonus of contractions and reduced the activity-area of contractions (P < 0.01). Anisomycin (100 mumol/l) did not change these effects or the spontaneous contractile activity. Removal or extracellular Ca2+ or addition of the L-type calcium channel blocker verapamil prevented the spontaneous as well as the progesterone-induced contractions, but had less pronounced effects on contractions initiated by oxytocin.
CONCLUSION: The results indicate that the actions of progesterone on term myometrial contractile activity occur without protein synthesis and that increased Ca2+ influx or decreased outward transport of Ca2+ may play a possible role)
DESIGN: Myometrial tissues were obtained from the lower uterine segment at elective Caesarean section of 30 term pregnant women. The contractile activity of muscle strips was measured by a superfusion technique and protein synthesis evaluated by [3H]-leucine incorporation.
RESULTS: [3H]-leucine incorporation into term myometrial strips was not affected by progesterone (10 mumol/l), but was markedly reduced by the protein synthesis inhibitor anisomycin (P < 0.05). However, progesterone increased frequency and tonus of contractions and reduced the activity-area of contractions (P < 0.01). Anisomycin (100 mumol/l) did not change these effects or the spontaneous contractile activity. Removal or extracellular Ca2+ or addition of the L-type calcium channel blocker verapamil prevented the spontaneous as well as the progesterone-induced contractions, but had less pronounced effects on contractions initiated by oxytocin.
CONCLUSION: The results indicate that the actions of progesterone on term myometrial contractile activity occur without protein synthesis and that increased Ca2+ influx or decreased outward transport of Ca2+ may play a possible role)