Activity of Sodium Ion, Potassium Ion in the Epididymis of the Rat
Ilio, Kenneth Yerro
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Permalink
https://hdl.handle.net/2142/72557
Description
Title
Activity of Sodium Ion, Potassium Ion in the Epididymis of the Rat
Author(s)
Ilio, Kenneth Yerro
Issue Date
1993
Doctoral Committee Chair(s)
Hess, R.A.,
Department of Study
Veterinary Medical Science
Discipline
Veterinary Medical Science
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Anatomy
Biology, Cell
Health Sciences, Toxicology
Abstract
Na$\sp+$,K$\sp+$-ATPase enzyme activity and its regulation was determined in the ductuli efferentes and the initial segment of the epididymis of the rat. Electron microscopic localization of Na$\sp+$,K$\sp+$-ATPase demonstrated enzyme activity along the cytoplasmic side of the plasmalemma of the ductal epithelial cells. The most intense deposition of reaction products was found on the plasmalemma delimiting the lower lateral and basal regions of non-ciliated cells. The plasma membranes in the apical regions of the cells were devoid of reaction product while the midlateral membranes showed a weak reaction. The enzymatic reaction was potassium-dependent and was inhibited by ouabain.
Quantitation of enzyme activity in isolated ductal segments showed that Na$\sp+$,K$\sp+$-ATPase is differentially distributed in four locations examined: highest in the proximal ductuli efferentes and initial segment of the epididymis, intermediate in the caput epididymidis and lowest in the conus region of the ductuli efferentes.
Ligation of the ductuli efferentes and castration decreased Na$\sp+$,K$\sp+$-ATPase activity in the four locations and treatment with testosterone and 5$\alpha$-dihydrotestosterone increased enzyme activity of castrated rats. It was concluded that androgens maintain the basic activity of Na$\sp+$,K$\sp+$-ATPase in the ductuli efferentes and the head of the epididymis and this action is possibly mediated by androgen receptors.
Estrogen treatment showed a selective modulating effect, depending on the hormonal status of the animal. When androgen was present, ATPase activity was reduced in all locations, however, when administered alone, either estrogen did not have an effect or it increased ATPase activity (in the conus region). This differential effect of estrogen on the Na$\sp+$,K$\sp+$-ATPase activity is probably mediated by estrogen receptors and could have a significant effect on the ionic environment surrounding the spermatozoa.
The effect of carbendazim, a benzimidazole fungicide which causes occlusions in the ductuli efferentes, on the Na$\sp+$,K$\sp+$-ATPase activity was determined. Single tubule incubations revealed that ATPase activity was increased by carbendazim in ductular regions corresponding to the major sites of occlusions. Because the enzyme is responsible for the movement of water from the lumen to interstitium, it was concluded that carbendazim-induced occlusions in the ductuli efferentes likely involves accelerated removal of water from the ductal lumen.
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