Expression and cellular localization of Na,K-ATPase isoforms in the rat ventral prostate.

OBJECTIVE To determine the expression and plasma membrane domain location of isoforms of Na,K-ATPase in the rat ventral prostate. MATERIALS AND METHODS Ventral prostate glands from adult male rats were dissected, cryosectioned (7 micro m) and attached to poly-l-lysine coated glass slides. The sections were then fixed in methanol and subjected to indirect immunofluorescence and immunoperoxidase procedures using a panel of well-characterized monoclonal and polyclonal antibodies raised against known Na,K-ATPase subunit isoforms. Immunofluorescence micrographs were digitally captured and analysed by image analysis software. RESULTS There was expression of Na,K-ATPase alpha1, beta1, beta2 and beta3 subunit isoforms in the lateral and basolateral plasma membrane domains of prostatic epithelial cells. The alpha1 isoform was abundant but there was no evidence of alpha2, alpha3 or gamma isoform expression in epithelial cells. The alpha3 isoform was not detected, but there was a relatively low level of alpha2 isoform expression in the smooth muscle and stroma. CONCLUSION Rat prostate Na,K-ATPase consists of alpha1/beta1, alpha1/beta2 and alpha1/beta3 isoenzymes. These isoform proteins were located in the lateral and basolateral plasma membrane domains of ventral prostatic epithelial cells. The distribution and subcellular localization of Na,K-ATPase is different in rodent and human prostate. Basolateral Na,K-ATPase probably contributes to the establishment of transepithelial ionic gradients that are a prerequisite for the uptake of metabolites by secondary active transport mechanisms and active citrate secretion.