Effects of protein synthesis inhibitor and antimicrotubular agent on transepithelial movement of 3H-androgens in the rat caput epididymis.

Abstract

The effects of protein synthesis inhibition and disassembly of microtubules in the epididymal epithelia on proluminal movement of 3H-androgens were investigated by using in vivo microperifusion of 3H-testosterone and subsequent micropuncture to obtain peritubular and intraluminal fluids of caput epididymal tubules. Cycloheximide (100 micrograms/ml) was used as protein synthesis inhibitor. Nocodazole (3 micrograms/ml) was used to depolymerize microtubules in the cell. The perifusion fluid was Minimum Essential Medium containing 26.7 microCi/ml 3H-testosterone and 1.3 microCi/ml 14C-polyethyleneglycol (14C-PEG), or the same fluid supplemented with cycloheximide or nocodazole. Radioactivity of 3H-androgen and 14C-PEG in perifusion and intraluminal fluids was determined at one hour after initiation of the sustaining perifusion, and the percentage of radioactivity of 3H-androgen and 14C-PEG appearing in the intraluminal fluid to that in the peritubular fluid was determined. Proluminal movement of 3H-androgens into the caput epididymal tubules in the control rats was 323.4 +/- 73.2%. This value was significantly reduced to 121.8 +/- 13% by addition of cycloheximide to the perifusion fluid (p < 0.01). Transepithelial movement of 3H-androgen in the caput epididymis was significantly decreased to 86.6 +/- 5.3% by exposure of the epididymal tubules to nocodazole (p < 0.01). Inhibition of protein synthesis and disassembly of microtubules in the epididymal epithelial cells completely eliminated antigrade proluminal movement of 3H-androgen into the tubules. Study of the incorporation of 35S-Methionine into epididymal tissue protein revealed significant reduction of the quantity of radiolabeled proteins in the perifused tissue with fluid containing cycloheximide (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)