The oocyte-cumulus complex (25 oocytes per 250 microL medium) produced prostaglandin-F2 alpha (PGF2 alpha) and PGE2 during maturation, immediately following fertilization and for at least 48 h after fertilization. The data suggest that PG production is important in the development of the oocyte; addition of PGE2 (5 ng mL-1) to the fertilization medium increased the rate of cleavage and groups of oocytes with low cleavage rates produced far less PG than groups with high cleavage rates. Measurement of PG in the maturation medium could therefore be a means of assessing the suitability of oocytes for fertilization.
The effect of Na pentobarbital anesthesia on serum secretin concentration and exocrine pancreatic secretian was investigated in dogs with chronic gastric and pancreatic fistulas. Na pentobarbital anesthesia was found 1) to reduce basal pancreatic flow rate by 74%, bicarbonate by 70% and protein secretions by 81 % withou t affecting basal immunoreaclive secretin (lRS) concentration; 2) to have no effect on Hel (9.6 mEq/30 min, intraduodenally) mediated IRS release but to reduce by approximately 50% Hel mediate!! bicarbonate output; 3) to have no effect on pancreatic responsiveness to stimulation by exogenous secretin (0.5 IU/kg x 30 min); 4) not to affect serum concentrations of IRS following secretin infusion. These data suggest 1) that basal pancreatic secretory functions are under con trol of tonic neural influences; 2) that Na pentobarbital anesthesia has no effect on IRS release but inhibits stimulated pancreatic bicarbonate secretion through suppression of an as yet unidentified agent; and 3) that Na pentobarbital does not affect the metaboIism of secretin. Furthermore, it was found that intraduodenal administration of 9.6 mEq of HCl and intravenous infusion of 0.5 IU/kg of secretin for 30 min both resulted in similar IRS concentrations of approximately 600 pU/mi (equivalent to 150 pg/ml).
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The effect of bovine LH on bovine uterine tissue from three phases of the oestrous cycle was studied. It was found that in the luteal phase the endometrium, myometrium and cervix contain a LH receptor (LH‐R) mRNA transcript and the 93 kDa receptor protein. Both LH‐R protein and its mRNA were also found in the uterine vein but mainly at pre‐oestus/oestrus. Incubation of cervical minces from the luteal phase with LH significantly increased (p < 0.05) the intracellular cAMP, inositol phosphate and cyclooxygenase as well as the production of PGE2 but not PGF2α. Induction of endometrial cyclooxygenase by LH is associated with release of PGF2α in the late luteal phase and 2 to 4 days postovulation. In contrast, in the pre‐oestrous/oestrous uterine vein, the signal for the transcript for LH‐R and the LH‐R protein was significantly higher than at other stages of the cycle. Incubation of uterine vein minces from pre‐oestrus/oestrus with LH significantly increased intracellular concentration of cyclooxygenase as well as production of both PGE2 and PGF2α. The presence of physiologically active LH‐R in the uterine tissue suggests a direct involvement of LH in uterine function, i.e. uterine relaxation by cAMP and PGE2 and regression of the corpus luteum by uterine PGF2α.
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