Forskolin effects on longitudinal myometrial strips from the pregnant rat: relationship with membrane potential and cyclic AMP.
The effects of forskolin on tension, membrane potential and cyclic AMP accumulation were studied in longitudinal myometrial strips from pregnant rats. 0.1 microM forskolin reduced the amplitude of spontaneous contractions by decreasing the frequency of action potential discharge without a change in resting potential or cyclic AMP accumulation. Forskolin, 1.0 microM, abolished contractions and action potentials, hyperpolarized the membrane and increased cyclic AMP accumulation. Ouabain, 1 mM, depolarized the muscle and increased resting tension. Ouabain reduced potential change produced by forskolin but did not prevent the relaxation or cAMP accumulation. Therefore changes in membrane potential are not prerequisite for the inhibitory actions of forskolin. The cyclic AMP-related relaxation may result primarily from intracellular events that remove calcium from the contractile elements.
D000818:Animals; D005576:Colforsin / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009215:Myometrium / Q000187:drug effects / Q000502:physiology*; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000502:physiology; D011247:Pregnancy; D051381:Rats; D014590:Uterine Contraction / Q000187:drug effects*
D005576:Colforsin; D010042:Ouabain; D000242:Cyclic AMP; D011188:Potassium