[Changes in potassium channel currents of prostate epithelial cell of old rats and significance thereof].

OBJECTIVE

To investigate the potassium channel currents and response thereof to the blocker of potassium channel in epithelium of prostate of Sprague Dawley (SD) rats.

METHODS

The dorsolateral lobes of prostates of 20 3-month-old (adult) male SD rats and 20 12-month-old (elderly) SD rats were removed, cut into small pieces of the size of 1 approximately 2 mm(3) in phosphate-buffered Ca(2+)-free Ringer's solution, and digested by collagenase IV for 25 min. Then the tissue chunks were put into fresh solution and gently agitated. These cells were cultured for one week. Pan-keratin immunocytochemistry was conducted. The potassium channel current of the prostate epithelium was recorded by whole-cell voltage clamp. Tetraethylammonium (TEA), a blocker of calcium-activated potassium channel of the concentration of 1 mmol/L, and 1 mol/L + 1 mmol/L 4-aminopyridine (4-AP), blocker of voltage-dependent potassium channel inhibitor, were sequentially added into the extra-cellular fluid and the current density was recorded.

RESULTS

TEA specifically inhibited the K(Ca) current After the addition of TEA and TEA + 4-AP, the current density at the potential of +80 mv of the 12-month-old rats was (18.48 +/- 1.7) pA/pF, significantly higher than that of the 3-month-old rats [(10.84 +/- 1.54) pA/pF, P < 0.01]. The original peak current of the 3-month-old rats was (9.5 +/- 1.8) pA/pF and became (5.4 +/- 3.1) pA/pF after the addition of TEA, decreased by 44% (P < 0.01); and the peak current of the 12-month-old rats was (19.1 +/- 2.9) pA/pF and became (7.2 +/- 3.2) pA/pF after the addition of TEA, decreased by 63% (P < 0.01).

CONCLUSION

Elderly rats have stronger potassium channel currents than adult rats, and their K(Ca) current is more sensitively to TEA. Aging is related to decreased prostate gland cell secretion.