title: Regional differences in bioelectrical properties and anion secretion in cultured epithelia from rat and human male excurrent ducts.
abstract: Bioelectrical properties and anion secretion in cultured epithelia from different regions of rat and human male excurrent ducts were studied by measuring the short-circuit currents (ISC). In all regions of the rat excurrent duct, Cl- secretion accounts for over 90% of the basal ISC, although the magnitude varied in different regions. Cl- secretion was found to be mediated by a Cl-/HCO3- exchanger, an Na+/H+ exchanger, and an Na+/K+/2Cl- symport located on the basolateral side of the epithelial cells. Forskolin, an activator of adenylate cyclase, and ionomycin, a Ca2+ ionophore, were used to investigate the relative importance of cAMP and Ca2+ as intracellular messengers regulating Cl- secretion in different regions. It was found that in both species, the forskolin-evoked ISC response was larger in the proximal end (efferent duct/caput epididymidis [rat/human, respectively]) than in the distal end (cauda/corpus epididymidis). The response to ionomycin in the rat cauda epididymidis (distal end) was larger than that in the efferent duct (proximal end); on the other hand, no significant difference in the ionomycin-induced ISC was observed in the caput and the corpus regions from the human epididymis. Our results indicate that while the cAMP- and Ca(2+)-dependent pathways are both involved in regulating Cl- secretion in all regions along the male excurrent ducts in both species, a regional difference exists with respect to the relative importance of the two regulatory pathways involved in Cl- secretion along the male reproductive tract.
authors.affiliation: Department of Physiology, Faculty of Medicine, Chinese University of Hong Kong, Shatin, N.T.
authors.forename: H C
authors.initials: HC
authors.lastname: Chan
authors.forename: K B
authors.initials: KB
authors.lastname: Lai
authors.forename: W O
authors.initials: WO
authors.lastname: Fu
authors.forename: Y W
authors.initials: YW
authors.lastname: Chung
authors.forename: P S
authors.initials: PS
authors.lastname: Chan
authors.forename: P Y
authors.initials: PY
authors.lastname: Wong
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D046508:Culture Techniques; D000242:Cyclic AMP / Q000378:metabolism; D004543:Ejaculatory Ducts / Q000187:drug effects / Q000378:metabolism*; D004563:Electrochemistry; D004822:Epididymis / Q000187:drug effects / Q000378:metabolism; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D017136:Ion Transport / Q000187:drug effects; D015759:Ionomycin / Q000494:pharmacology; D008297:Male; D051381:Rats; D015290:Second Messenger Systems
chemical_list: D002712:Chlorides; D005576:Colforsin; D015759:Ionomycin; D000242:Cyclic AMP; D002118:Calcium