AJP - Cell Physiology, Vol 233, Issue 5 180-C187, Copyright © 1977 by American Physiological Society
Bioelectrical and contractile behavior of rabbit mesotubarium superius: estrogen withdrawal
J. T. Conrad
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.
