Non-genomic mechanism of action of delta-4 and 5-reduced androgens and progestins on the contractility of the isolated rat myometrium.
Effective concentrations50 of androgens, i.e. testosterone, androsterone, androstanediol, 5 beta-dihydrotestosterone and progestins: progesterone, pregnanolone, pregnanedione, epipregnanolone, allopregnanolone and allopregnanedione were assayed on the tonic contractions of the isolated rat myometrium induced by calcium in high-potassium calcium-free depolarizant solutions. Steroids showed their relaxant effect by fadding the sustained contraction induced by calcium in a depolarized state. Also, the addition of the calcium ionophores A-23187 and X-537A reversed the steroid relaxant effect by increasing sharply the tonic contraction. The possibility of steroid-induced relaxation through release of noradrenaline or histamine was discarded by blocking their specific receptors. From the results it is concluded that delta-4 and 5-reduced androgens and progestins produce relaxation by a myogenic mechanism acting on the smooth muscle cell, most likely by directly blocking the calcium channels they causing modulation of: the contraction-relaxation cycle.
Perusquía
M
M
Unidad de Investigación Biomédica del CMN, IMSS, México D.F., Mexico.
García-Yañez
E
E
Ibáñez
R
R
Kubli-Garfias
C
C
D000728:Androgens / Q000494:pharmacology*; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology; D013196:Dihydrotestosterone / Q000494:pharmacology; D005260:Female; D007832:Lasalocid / Q000494:pharmacology; D009126:Muscle Relaxation / Q000187:drug effects; D009215:Myometrium / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology; D011277:Pregnanediones / Q000494:pharmacology; D011280:Pregnanolone / Q000494:pharmacology; D011372:Progestins / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D014590:Uterine Contraction / Q000187:drug effects*
D000728:Androgens; D015220:Calcium Channels; D011277:Pregnanediones; D011372:Progestins; D013196:Dihydrotestosterone; D000001:Calcimycin; D011280:Pregnanolone; D011188:Potassium; D002118:Calcium; D007832:Lasalocid