Bioelectrical and contractile behavior of rabbit mesotubarium superius: estrogen withdrawal.
The mesotubarium superius of the female rabbit is a thin, plane sheet of smooth muscle responding to the in vivo endocrine states of ovulation, estrous, castration, pregnancy, and replacement estrogen therapy of the castrate in a manner similar to that of the uterus. Both isometric tension and microelectrode recorded transmembrane potentials were measured in vitro to make these comparisons. In addition, confirmation of the "estrogen-withdrawal" theory of activation was obtained when it was noted that about 12 h after an abrupt withdrawal of estrogen there is an increase in contractile activity coinciding with an increase in subthreshold activity and a slight (about 5 mV) decline in the average resting potential compared to the control estrous level. It is concluded that the mesotubarium superius is an excellent tissue for reproductive smooth muscle studies, where a geometrically simple model is useful.
D000818:Animals; D002369:Castration; D004971:Estrus; D005187:Fallopian Tubes / Q000502:physiology; D005260:Female; D008564:Membrane Potentials; D008954:Models, Biological; D009119:Muscle Contraction; D009129:Muscle Tonus; D009130:Muscle, Smooth / Q000502:physiology*; D011247:Pregnancy; D011817:Rabbits