AJP - Endocrinology and Metabolism, Vol 238, Issue 2 157-E166, Copyright © 1980 by American Physiological Society
Role of prostaglandins in contractile activity of the ampulla of the rabbit oviduct
M. J. Harper, L. W. Coons, D. A. Radicke, B. J. Hodgson and G. Valenzuela
Contractile activity of the ampulla of rabbit oviducts removed 24 h after
an ovulating injection was studied in vitro. Spontaneous activity,
field-stimulated activity, and response to phenylephrine were studied in
normal, reversed, and scraped (endosalpinx removed) sections of tissues in
the presence or absence of inhibitors of prostaglandin synthetase (8 or 51
micrograms/ml indomethacin or 10 or 100 micrograms/ml
5,8,11,14-eicosatetraynoic acid (ETA)). The effects of in vivo treatment
with 10 mg/kg of indomethacin on the same responses were examined. Scraped
tissues produced more prostaglandin E and F (measured by radioimmunoassay)
than did normal tissues, and this production was suppressed by 10
micrograms/ml of indomethacin or 100 micrograms/ml of ETA. Production of
prostaglandin by normal tissues was not depressed by these compounds in
vitro, but was significantly reduced by pretreatment of the animals with
indomethacin in vivo. In the absence of the endosalpinx, the myosalpinx
exhibited spontaneous activity and responded to field stimulation and
phenylephrine. Scraped and reversed tissues, however, showed a faster
decline in response to field stimulation than normal tissues, and this was
due to the traumatization. By contrast, traumatization increased the
sensitivity of the tissue to respond to phenylephrine. Inhibition of
prostaglandin synthetase by low doses of indomethacin or ETA prevented
desensitization of the tissue to field stimulation, but this
desensitization was little affected by the higher doses of indomethacin in
vitro or in vivo. ETA did not affect the phenylephrine dose-response curves
and nor did 8 micrograms/ml of indomethacin, whereas the high dose was
inhibitory. Spontaneous activity was only affected by the in vivo
pretreatment with indomethacin, which prevented the decline in activity of
scraped tissue with time.
