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This Article Full Text Full Text (PDF) All Versions of this Article: 295/1/E55    most recent 00714.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Rajagopal, M. Articles by Widdicombe, J. H. PubMed PubMed Citation Articles by Rajagopal, M. Articles by Widdicombe, J. H.

Hormonal and purinergic stimulation of bicarbonate secretion in oviducts of rhesus monkey

¹Department of Physiology and Membrane Biology, University of California-Davis, Davis; and ²Children's Hospital Oakland Research Institute, Oakland, California

Submitted 8 November 2007 ; accepted in final form 11 April 2008

Because an increase in the HCO₃^– concentration of oviductal liquid at midcycle is believed to markedly enhance fertility, we have studied active secretion of HCO₃^– across highly differentiated cultures of monkey oviductal epithelium. Cultured cell sheets were mounted in Ussing chambers and bathed in medium containing 25 mM HCO₃^–. Purinergic agents potently stimulated short-circuit current (I_sc) with an initial transient response declining within 2 min to a sustained response. The potency sequence of ATP UTP > ADP >> AMP suggested that the I_sc response was mediated mainly by P2Y₂ receptors. Acetazolamide, an inhibitor of carbonic anhydrase, had little or no effect on baseline I_sc or the transient response to ATP but abolished the sustained response to ATP. Similar results were obtained on sheets of native epithelium. In pH-stat experiments, the abluminal medium of cell cultures was bathed in HCO₃^–-CO₂ medium, and the pH of the unbuffered luminal medium was maintained at 7.4 by addition of strong acid or base. ATP stimulated base secretion, and this was inhibited by acetazolamide. Furthermore, these changes in secretion of base were in good quantitative agreement with the I_sc responses. When phenol red (an estrogen) was removed from the culture medium, ATP-dependent HCO₃^– secretion was markedly reduced but could be restored by treatment with estradiol. Estrogens also markedly increased ciliation of the cultures. These results suggest that the midcycle increase in the HCO₃^– concentration of oviductal liquid may be mediated by the effects of estradiol on purinergic pathways or on ATP secretion.

carbonic anhydrase; short-circuit current; estradiol; adenosine 5'-triphosphate