OVIDUCT FLUID PH IN INTACT AND UNILATERALLY OVARIECTOMIZED PIGS

The pH of the oviduct lumen was measured at different stages of the es trous cycle in the ampulla and ampullary-isthmic junction (AIJ) of int act and unilaterally ovariectomized mated or nonmated pigs. The pH pro file consisted of high frequency small peaks superimposed on low frequ ency large amplitude peaks. One animal examined at midcycle exhibited fluctuations in pH (peak to nadir; Delta pH) of 0.3 and 0.7 units in t he ampulla and AIJ, respectively, and the frequencies of the large pea ks in these regions were 2.6 and 1.6 peaks.min(-1), respectively. In s ix preovulatory unmated pigs, the Delta pH (mean +/- SE) was 0.50 +/- 0.04 units in both regions and the large peak frequencies were 0.6 +/- 0.06 peaks.min(-1). In one animal that was assessed during ovulation, the pH showed deviations of up to 0.4 pH units, which were probably d ue to the alkalinity of follicular fluid accompanying the ovulated egg s. In the ampullae of five unilaterally ovariectomized postovulatory-m ated pigs, the Delta pH in oviducts with and without an ipsilateral ov ary was significantly lower than preovulatory (p < 0.05), but the larg e and the small peak frequencies were not significantly different. By contrast, the Delta pH in the AIJ with an ipsilateral ovary (0.11 +/- 0.02 units) was significantly lower than before ovulation (0.54 +/- 0. 04 units) and also when compared with the contralateral AIJ (0.36 +/- 0.06 units) (p < 0.05). The ovary also influenced the small peak frequ ency, which was significantly higher if the ipsilateral ovary was abse nt (10.7 +/- 1.5 vs. 14.9 +/- 1.6 peaks.min(-1), respectively). Thus, oviduct fluid pH is controlled by both systemic and local mechanisms, and the ipsilateral ovary and (or) embryonic factors influence the pH profile of the oviduct.