Ionic and pharmacologic characteristics of epithelial cells in a semi‐intact preparation of the rat ventral prostate gland

Abstract

It was concluded that the basal membrane potential of prostatic epithelial cells is associated with a relatively high Na(+):K(+) permeability ratio and metabolic dependence. The hormonal and pharmacologic sensitivity observed is consistent with the functional characteristics of the prostate gland.

Endogenous and exogenous citrate transport and release in prostatic preparations: semi-polarized two-dimensional cultures of human PNT2-C2 cells and isolated tubules and segments of rat prostate

“…However, the effects of the various substances tested were not exclusive to one side or another, so it is highly likely that the PNT2-C2 epithelium that formed had only limited polarization. Consistent with a prostatic epithelium being generated, we found that the TEPD was sensitive to citrate (as we showed in vivo previously; [14]). Aspartate is required for synthesis of citrate within prostatic epithelial cells [23] and is thought to be taken up by them via a Na þ -dependent high affinity transporter [24].…”

“…The amount of citrate released from segments of rat prostate was measured by the spectrophotometric ''citrate lyase method'' described earlier [8,11]. Prostate segments were obtained as described previously [13,14]. Briefly, a dissected rat prostate gland was tore into small (3-5 mm) pieces using two needles and individual segments were placed into 96-well dishes, washed carefully and covered with 50 ml of normal EB solution (normal or with modified ionic content) [8].…”

“…Release of endogenous citrate in the lumen of rat prostatic tubules was also studied. Rat prostate was dissected as described earlier [13,14]. The whole gland was incubated in EB solution with 80 U/ml collage-nase, 400 U/ml hyaluronidase and 2 mg/ml bovine serum albumin (BSA) at 378C with 5% CO 2 .…”

“…We have previously shown that small pieces of rat prostate are physiologically viable and will respond to a range of pharmacological agents (e.g. testosterone, adrenaline, insulin) related to prostatic function [14]. The same preparation was used in the present study to investigate release of endogeneous citrate.…”

Citrate transport and metabolism in mammalian cells

“…(38) The K þ -citrate co-transport mechanism is electrogenic and hyperpolarises the apical membrane. (39) The inside-negative membrane potential is expected to impede the efflux of citrate via this K þ -citrate co-transport mechanism, but the involvement of four K þ in the transport process will overcome this negative effect of membrane potential and actively pump citrate out of the cell against a concentration gradient. This process is facilitated further by the re-entry of K þ back into the cells via a H þ /K þ -ATPase localised in the apical membrane.…”