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Biology of Reproduction, Vol 15, 58-65, Copyright © 1976 by Society for the Study of Reproduction
and Periarterial Sympathetic Nerve Stimulation
1 Departments of Animal Science and Department of Pharmacology,
Oregon State University,
Corvallis, Oregon 97331 Experiments were conducted to study the in vitro responses of bovine and ovine uterine arterial
smooth muscle to prostaglandin F2 Baseline perfusion pressure, recorded for each arterial segment following a 30-min initial
equilibration, was higher (P<0.01) for arteries ipsilateral to ovaries bearing corpora lutes (CL) in
heifers and ewes. Overall responsiveness to SES of arteries ipsilateral to ovaries bearing CL from
both species was greater (P<0.01) than for arteries from the contralateral side only in nonpregnant
animals. Arteries from nonpregnant heifers perfused with PGF2
and periarterial sympathetic nerve stimulation. Five
nonpregnant and five pregnant beef heifers and ten nonpregnant and five pregnant unilaterally-ovulating ewes were utilized. Heifers and ewes were necropsied on Days 17 and 15 after detected
estrus, respectively. A 3.5 cm segment of the uterine artery supplying each uterine horn was
removed immediately proximal to its first bifurcation in the mesometrium. Oxygenated Krebs at
37°C was perfused into the arterial segments mounted in duplicate perfusion chambers at a rate of
17 and 10 ml/min for arterial segments from heifers and ewes, respectively. Changes in perfusion
pressure due to changes in resistance to flow through the arterial segment were recorded in mm Hg.
Saline, prostaglandin F2-tromethamine salt (PGF2, 1 ng/ml final concentration) and saline, in
that order, were each perfused for 30 min into the perfusion cannulae at a rate of 0.07 ml/min.
Arteries from five nonpregnant ewes also received a perfusion of conceptus brei in uterine
flushings, prepared from Day 15 pregnant ewes, for 30 mm prior to the PGF2 perfusion. During
each 30-min perfusion, periarterial sympathetic nerves were subjected to sequential electrical
stimulations (SES) which were applied at 10-min intervals and the resultant vascular smooth
muscle contractions recorded. exhibited greater (P<0.01)
smooth muscle contractility in response to SES than when arteries were perfused with saline.
Similarly, arteries from nonpregnant ewes responded to SES during PGF2 perfusion with
increased contractility when compared to arterial responses to SES during saline control
perfusions; however, only the increase in responsiveness of arteries contralateral to ovaries bearing
CL was significant (P<0.05). Perfusion of arteries from pregnant animals with PGF2 resulted in
no change in arterial responsiveness (heifers) or a decrease (P<0.05) in arterial responsiveness
(ewes) to SES when compared to responses during respective saline control perfusions before and
after PGF2. Perfusion of conceptus brei in uterine flushings for 30 minutes, although having no
effect on arterial responsiveness to SES alone, caused a pronounced decrease (P<0.01) in
responsiveness of arteries to SES during a subsequent perfusion of PGF2.
Note:
ACKNOWLEDGMENTS
The authors gratefully acknowledge Dr. W. H.
Kennick and Mr. R. Turner, Meat Science Laboratory,
for their assistance and Dr. John Pike, The Upjohn
Company, for the gift of prostaglandin F2-tromethamine salt.
This article has been cited by other articles:
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  F. Stormshak and C. V. Bishop BOARD-INVITED REVIEW: Estrogen and progesterone signaling: Genomic and nongenomic actions in domestic ruminants J Anim Sci, February 1, 2008; 86(2): 299 - 315. [Abstract] [Full Text] [PDF]
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