Porcine Vas Deferens Luminal pH Is Acutely Increased by Systemic Xylazine Administration1

Abstract

Data are accumulating to demonstrate that pH regulation in the male reproductive tract has a vital role in modulating sperm cell fertilizing capacity, and therefore male fertility. Bicarbonate uptake by sperm cells is required for the achievement of motility levels required for fertilization. Vas deferens epithelial cells can carry out measurable bicarbonate secretion, but the available literature to date reports that the vas deferens luminal content is typically acidic. This study aimed to determine pH in the boar vas deferens lumen and whether modulatory mechanisms exist for regulation of pH in this compartment of the male reproductive tract. A fiberoptic pH probe was used to assess pH in the vas deferens of anesthetized adult boars. The mean pH, derived from multiple measurements at variable positions along the vas deferens lumen, was 7.39 +/- 0.09. Furthermore, administration of xylazine, an alpha-2 adrenergic receptor agonist rapidly (<10 min) alkalinized the vas deferens lumen in most cases. Because the duct was transected proximal to the site of measurements, the observations rule out the possibility that alkalinization resulted from secretion in more proximal portions of the duct. These results indicate that the boar vas deferens lumen can be alkaline, and they suggest that porcine vas deferens epithelia increase net bicarbonate secretion in vivo after systemic alpha-2 adrenergic stimulation. This secretory response greatly changes the luminal environment to which sperm cells are exposed, which will initiate or enhance motility, and is expected to modulate male fertility.

Relative contribution of clear cells and principal cells to luminal pH in the mouse epididymis†

“…We showed that like the pancreas, epididymal CFTR is involved in bicarbonate secretion, and NHE3 mediates proton secretion by PCs to regulate/ maintain luminal pH. We and others have previously shown that CFTR is expressed in the apical membrane of PCs [43,50,59], and our results are in agreement with previous studies showing the role of CFTR in chloride and bicarbonate secretion in primary cultures of rat cauda epithelial cells [32][33][34][35], and in the porcine vas deferens perfused in vivo [60]. In addition, we observed an inhibition of proton secretion by EIPA, indicating the participation of an NHE in the recovery from an alkaline luminal pH.…”

Establishment of Cell-Cell Cross Talk in the Epididymis: Control of Luminal Acidification

“…Principal Cell‐Clear Cell Cross Talk— Basolateral stimulation of the epididymal epithelium triggers bicarbonate secretion by principal cells (Leung et al, 1992; Wong, 1998; Sedlacek et al, 2001; Carlin et al, 2003; Hagedorn et al, 2007; Pierucci‐Alves and Schultz, 2008; Pierucci‐Alves et al, 2010). This leads to a subsequent rise in luminal bicarbonate concentration, which was proposed to prime spermatozoa before ejaculation (Carlin et al, 2003; Pierucci‐Alves et al, 2010). However, a sustained elevation in luminal bicarbonate concentration might be harmful to spermatozoa because it would maintain them in a preactivated state during storage.…”

Transforming growth factor-β1 impairs CFTR-mediated anion secretion across cultured porcine vas deferens epithelial monolayer via the p38 MAPK pathway

“…An acid environment is required for sperm to mature as they traverse the epididymis. However, an alkaline luminal pH is required to initiate motility and to induce fertilizing capacity of sperm cells (8,30,36). The critical role of CFTR in the male reproductive system has been demonstrated by the magnitude of infertility that is associated with CFTR mutations including the high frequency of CBAVD in both severely and mildly affected cystic fibrosis patients.…”