Pretreatment with porcine relaxin and Mg ions enhances inhibitory effects of dibutyryl cyclic AMP in longitudinal muscle of estrogen-treated rat myometrium.
Phasic contractions were evoked in Mg-free Krebs solution by electrical stimulation in the longitudinal myometrial strip taken from estrogen-treated rats, and the application of 30 microM dibutyryl cyclic AMP (db cAMP) for 15 min depressed the amplitude of contraction to 81 +/- 18% (+/- SD, n = 23) of the control. The contractile depression caused by db cAMP was not significantly altered by pretreatment with either 1 mM Mg (40 min) or 100 mU porcine relaxin (15 min) alone; however it was markedly enhanced to 22 +/- 30% (n = 7) of the control response by the combined pretreatment with Mg and relaxin. The enhancement lasted for longer than 2 h thereafter in Mg-free Krebs solution. It was discussed that some memory factor was induced by relaxin in the presence of 1 mM Mg to respond strongly to db cAMP.
Todoroki
N
N
Department of Physiology, Yamaguchi University, School of Medicine, Ube, Japan.
Osa
T
T
Cui
D
D
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology*; D004558:Electric Stimulation; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D009215:Myometrium / Q000187:drug effects* / Q000502:physiology; D010052:Ovariectomy; D051381:Rats; D017208:Rats, Wistar; D012065:Relaxin / Q000494:pharmacology*; D014590:Uterine Contraction / Q000187:drug effects*
D004958:Estradiol; D003994:Bucladesine; D012065:Relaxin; D008274:Magnesium