Stimulation of protein secretion in the initial segment of the rat epididymis by fluid from the ram rete testis

Abstract

Summary. Zone 1A of the ductus epididymidis was perfused with ovine rete testis fluid (nRTF) and modifications of it, and a synthetic medium (sRTF) based on the inorganic composition of nRTF. There was little fluid transport by the duct mucosa and nRTF stimulated protein secretion. The secretagogue activity was not extracted by charcoal, was sensitive to protease digestion and was present in a portion of nRTF with a molecular weight of > 10 000. The addition of bovine serum albumin to the sRTF stimulated protein secretion, but not to the same extent as equal amounts of protein in nRTF. Polyacrylamide gel electrophoresis of the perfusates showed that proteins with molecular weights of 19 000 (all rats studied), and 22 000, 30 000 and 60 000 (at least half the rats studied) were secreted into the perfusion fluids as well as some blood proteins, but the pattern of secretion was not affected by the composition of the perfusion fluid. Keywords: initial segment; rete testis fluid; secretagogue; rat