In vitro metabolism of glucose by bovine reproductive tissues obtained during the estrous cycle and after calving.
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Two experiments were conducted to determine the effect of physiological state (stage of the estrous cycle or time after calving) on the in vitro metabolism of glucose by reproductive tissues. In Exp. 1, the corpus luteum and ipsilateral uterine horn were collected at surgery from 15 cows at early (d 6 to 7), middle (d 10 to 13), or late (d 17 to 19) stages of the estrous cycle. Luteal or endometrial tissues (45 mg) were incubated (4 h, 37 degrees C) in metabolic flasks containing Nutrient Mixture F-10 (3 mL), increasing concentrations of glucose (1, 2, 5, 10, or 15 mM), and 1 microCi of [U-14C]glucose. Luteal tissue collected at the middle stage of the estrous cycle had greater (P less than .04) rates of glucose uptake (17.8 vs 12.1 ng/mg of wet tissue per min) and oxidation (138.6 vs 67.7 pg/mg of wet tissue per min) and a lower (P less than .02) rate of metabolism of glucose to lactate (10.5 vs 13.3 ng/mg of wet tissue per min) than tissue collected at the late stage. Compared to tissue collected at early and late stages, endometrial tissue collected at the middle stage of the estrous cycle had a similar (P greater than .5) rate of glucose uptake (29.6 vs 27.8 and 26.1 ng/mg of wet tissue per min), a lower (P less than .02) rate of metabolism of glucose to lactate (13.8 vs 16.6 and 16.4 ng/mg of wet tissue per min), and a greater (P less than .1) rate of oxidation of glucose (84.1 vs 65.8 and 72.3 pg/mg of wet tissue per min). In Exp. 2, the previously gravid uterine horn was collected at surgery on d 20 (n = 8) or 30 (n = 7) after calving, or the uterine horn ipsilateral to the preovulatory follicle was collected at first observed estrus after calving (n = 8). Uterine tissue obtained at first estrus after calving had a greater (P less than .003) rate of glucose uptake and oxidation (88.8 vs 77.3 and 75.5 pg/mg of tissue per min) than d-20 or d-30 endometrium.(ABSTRACT TRUNCATED AT 250 WORDS)
