Electrogenic anion secretion in cultured rat epididymal epithelium.

Abstract

SUMMARY1. Primarv monolayer cultures enriched with principal cells from rat cauda epididymis were grown on pervious supports until confluence was reached. The epithelia so formed were used for short-circuit current recording.2. Epididymal monolayers had a transepithelial potential of 0-2 mV (apical side negative), a basal short-circuit current of 2 ,uA/cm2 and a transepithelial resistance of 60-90 Q cm2 when bathed on both sides with Krebs-Henseleit solution at 37 0Cand gassed with 95aa O2-5aO CO2.3. 8-bromo-adenosine 3',5'-phosphate (1 mm) and forskolin (10 pM) caused an inward-flowing current in short-circuited monolayers. The current was partially sensitive to acetazolamide and to frusemide, suggesting that, anion secretion was responsible for the responses. In the absence of chloride in the bathing fluid the response to forskolin was sensitive to acetazolamide but not to frusemide. 4. The peptide lysylbradykinin (LBK) and prostaglandin E2 (PGE2) also produced inward-flowing currents which again appeared to be due to anion secretion. The actions of PGE2 were seen only when this agent was added to the basolateral side of the tissue, while LBK had effects from both sides. The responses to kinin, but not to PGE2. were inhibited by cyclo-oxygenase inhibitors such as piroxicam and indomethacin. It seems the kinin effects are dependent, at least in part, upon eicosanoid formation.5. Responses to kinin and PGE2 were severely attenuated in chloride-free bathing solution. Readdition of chloride-containing solution restored the responses to both agents.6. Assuming electrogenic ion secretion in the epididymis is accompanied by osmotic fluid flow it is evident that the transit time of sperm in the cauda epididymis will be reduced. Possible consequences for the maturation of spermatozoa are discussed.

Endothelin stimulates short circuit current in a cultured epithelium

“…The EC50 value obtained in rat epididymis is about half an order to one order of magnitude higher than that required for vascular smooth muscle contraction (Yanagisawa et al, 1988) but is about one order of magnitude lower than that required for stimulation of contraction in the human isolated urinary bladder (Maggi et al, 1989). The receptors mediating the effect in the epididymis are distinct from those of angiotensin, bradykinin and adrenaline (Figure 4) although the effects of endothelin, bradykinin (Cuthbert & Wong, 1986) and angiotensin II (Wong, 1988a) are mediated by an increase in prostaglandin synthesis.…”

“…Measurement ofshort circuit current (SCC) Primary monolayer cultures of rat cauda epididymis were grown on millipore filters by methods described previously (Cuthbert & Wong, 1986;Wong, 1988a, b, c). After 4 days of culture, the monolayer became confluent and was ready for the measurement of electrogenic anion secretion by the short circuit current technique.…”

“…The rise in SCC stimulated by endothelin was (Wong & Chan, 1988 intracellular cyclic AMP as the second messenger (Cuthbert & Wong, 1986;Wong, 1988a (Table 2).…”

“…This epihelium has been shown to secrete anions electrogenically when stimulated with secretory agonists that increase the level of intracellular cyclic AMP (Cuthbert & Wong, 1986;Wong, 1988a, b, c).…”

Regulated anion secretion in cultured epithelia from Sertoli cells of immature rats

“…Such assembly forms a well into which Sertoli cells could be seeded (Cuthbert & Wong, 1986;Wong, 1988a). Freshly isolated Sertoli cells suspended in DMEM-F12 were plated into the wells at a cell density of 25 ² 10AE cells filter¢.…”