Removal and restoration of epithelial chloride secretory activity of kinins by gene manipulation

Bradykinin-stimulated cyclooxygenase activity stimulates vas deferens epithelial anion secretion in vitro in swine and humans

Epithelia lining the male reproductive duct modulate fertility by altering the luminal environment to which sperm are exposed. Although vas deferens epithelial cells reportedly express high levels of cyclooxygenases (Ptgs), and activation of bradykinin (BK) receptors can lead to upregulation of PTGS activity in epididymal epithelia, it remains unknown whether BKs and/or PTGSs have any role in modulating epithelial ion transport across vas deferens epithelia. Porcine and human vas deferens epithelial cell primary cultures and the PVD9902 cell line responded to lysylbradykinin with an increase in short circuit current (I SC; indicating net anion secretion), an effect that was 60%-93% reduced by indomethacin. The BK effect was inhibited by the B2 receptor subtype (BDKRB2) antagonist HOE140, whereas the B1 receptor subtype agonist des-Arg9-BK had no effect. BDKRB2 immunoreactivity was documented in most epithelial cells composing the native epithelium and on Western blots derived from cultured cells. Gene expression analysis revealed that the PTGS2 transcript is 20 times more abundant than its PTGS1 counterpart in cultured porcine vas deferens epithelia and that BDKRB2 mRNA is likewise highly expressed. Subsequent experiments revealed that prostaglandin E2, 1-OH prostaglandin E1 (prostaglandin E receptor 4 [PTGER4] agonist) and butaprost (PTGER2 agonist) increase I SC in a concentration-dependent manner, whereas sulprostone (mixed PTGER1 and PTGER3 agonist) produced no change in I SC. These results demonstrate that autacoids can affect epithelial cells to acutely modulate the luminal environment to which sperm are exposed in the vas deferens by enhancing PTGS activity, leading to the production of prostaglandins that act at PTGER4 and/or PTGER2 to induce or enhance anion secretion.

Induction of bradykinin B1 receptors in rat colonic epithelium

1. Des-Arg9 bradykinin (DAB), a classical B1-kinin receptor agonist was without effect when applied to the basolateral surface of rat isolated colon epithelium. Three hours after tissues were isolated DAB caused, after a delay of up to 2 min, a maintained increase of short circuit current (SCC). 2. The SCC increase in colonic epithelia, mounted in vitro for three hours, caused by DAB was due to electrogenic chloride secretion as the current increase was reversed by frusemide and did not occur in the absence of cystic fibrosis transmembrane conductance regulator (CFTR) chloride channels. The EC50 for DAB was approximately 50 nM. 3. An inhibitor of transcription (actinomycin D) and of translation (cycloheximide) prevented the appearance of DAB sensitivity without affecting the responses to another secretagogue (forskolin). 4. The classical B1-kinin receptor antagonist, Leu8-des-Arg9 bradykinin, was shown to be an agonist in rat colon epithelium. Other B1-kinin receptor antagonists (des-Arg10-Hoe 140 and R-715) inhibited the responses to DAB in 'aged' colonic epithelia, and the inhibition was easily surmounted by increasing the concentration of DAB. 5. Response to DAB did not appear to involve to any significant extent, the formation of prostaglandins, leukotrienes, histamine or nitric oxide. Furthermore, no neuronal involvement was apparent in the stripped colonic preparations. The responses to DAB were not significantly different in epithelia taken from different parts of the distal colon. 6. The differences between the responses of the colonic epithelium to B1- and B2-kinin receptor agonists are discussed.