title: Rapid effects of estrogen and progesterone on tone and spontaneous rhythmic contractions of the rabbit bladder.
abstract: Previous studies indicate that bladder instability in man may be associated with increased spontaneous rhythmic contractile activity. Ca(2+) influx plays a central role in smooth muscle contractions, and recent evidence suggests that steroid hormones rapidly affect Ca(2+) influx. Therefore we tested the hypothesis that estrogen and progesterone modulates spontaneous rhythmic detrusor contractions. Tissues were secured to isometric force (F) transducers in tissue baths and length-adjusted until K(+)-depolarization produced maximum contractions (F(o)). Spontaneous rhythmic contractions (SRC) were sampled before and immediately after addition of estradiol or progesterone (10(-5) M) to tissue baths. The average frequency and amplitude of SRC were, respectively, 0.156 Hz and 0.053 F/F(o) (n = 24). Estradiol caused an immediate reduction in SRC, such that by 10 min, tone, frequency and amplitude were each reduced by, respectively, 36%, 46% and 47% (n = 7, P < 0.05). However, progesterone caused an immediate weak contraction, and at steady state (10 min), progesterone increased frequency of SRC by 152% but decreased SRC amplitude by 50% (n = 10, P < 0.05). Novel therapies using unique steroids that do not interact with genomic receptors may potentially reduce bladder smooth muscle activity, thereby reducing detrusor instability.
authors.affiliation: Department of Urology, Eastern Virginia Medical School, Norfolk, Virginia, USA.
authors.forename: O Z
authors.initials: OZ
authors.lastname: Shenfeld
authors.forename: K A
authors.initials: KA
authors.lastname: McCammon
authors.forename: P F
authors.initials: PF
authors.lastname: Blackmore
authors.forename: P H
authors.initials: PH
authors.lastname: Ratz
mesh_terms: D000818:Animals; D004958:Estradiol / Q000494:pharmacology*; D000431:Ethanol / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D009043:Motor Activity / Q000187:drug effects*; D009119:Muscle Contraction / Q000187:drug effects; D009129:Muscle Tonus / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects; D010507:Periodicity; D011374:Progesterone / Q000494:pharmacology*; D011817:Rabbits; D013997:Time Factors; D001743:Urinary Bladder / Q000187:drug effects* / Q000502:physiology
chemical_list: D000431:Ethanol; D011374:Progesterone; D004958:Estradiol