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PROGESTERONE CONCENTRATION, INTRALUMINAL PRESSURE AND ELECTRICAL ACTIVITY OF THE GUINEA-PIG UTERUS

1974; Bioscientifica; Volume: 61; Issue: 2 Linguagem: Inglês

10.1677/joe.0.0610255

1479-6805

D. G. Porter, K. Yoshinaga, J. H. Ford,

Reproductive Physiology in Livestock

SUMMARY The electrical activity of the myometrium and the intra-uterine pressure were recorded by means of suction electrodes and intraluminal balloons respectively from anaesthetized, oestrogen-primed, ovariectomized guinea-pigs treated with progesterone (25 mg, s.c. twice, 16 h apart). No loss of intra-uterine pressure occurred after progesterone treatment and electrical activities in the balloon-containing and intact horns were indistinguishable. Furthermore, the concentration of progesterone in the uteri of these animals was 0·32 ± 0·05 ( S.E.M. ) μg (balloon-containing horn) and 0·43 ± 0·06 μ/g wet tissue (intact horn). These values greatly exceed the levels found in uteri of pregnant animals (0·07 ± 0·03 μ/g wet tissue). Thus the failure of progesterone to reduce myometrial activity in the guinea-pig is real and is not due to interference from the balloon, or to failure of the steroid to reach the uterine muscle or to lack of oestrogen priming.