Transepithelial voltage changes during prostatic secretion in the dog

Abstract

To define the nature of Na+, K+, and Cl- secretion by the dog prostate, the electrical potential difference between fluid in the prostatic urethra and venous blood was recorded during secretion provoked in pentobarbital-anesthetized dogs by electrically stimulating the hypogastric nerves or by administering pilocarpine intravenously. The resultant prostatic fluid samples as well as plasma samples taken before and/or after secretion were analyzed for these electrolytes. During secretion provoked by either means the transepithelial electrical potential difference, which was essentially zero at rest, became lumen negative, the maximum change (which was related to gland size) being about 4 mV. The time courses of both the potential change and the secretion of fluid were very similar. The Na+ concentration in both nerve- and pilocarpine-induced prostatic fluid was equal to that in plasma, whereas the K+ and Cl- concentrations were higher than in plasma. It is concluded that Na+ may move passively from plasma into prostatic fluid, perhaps via the paracellular route, but the movement of K+ and Cl- probably involves active transcellular transport.