老年SD大鼠前列腺上皮细胞膜钾离子通道变化及意义

目的探讨雄性SD大鼠前列腺上皮细胞膜钾离子通道电流的变化和对钾通道阻断剂的反应。方法分别取3个月龄成年和12个月龄的老年SD大鼠的背外侧叶前列腺组织,剪成1—2mm^3大小,经消化、培养、免疫组鉴别,将形态正常、贴壁良好的腺上皮细胞用全细胞膜片钳模式记录钾通道电流。结果成年和老年SD大鼠的前列腺上皮细胞膜＋80mV钾电流密度分别为（10．84±1．54）pA／pF vs（18．48±1．7）pA／pF（n=20,P〈0．01）;钙激活型钾通道抑制剂（KCa通道）四乙胺（TEA）对老年大鼠峰电流阻断从19．1±2．9到7．2±3．2,KCa电流被抑制约63％;成年大鼠为9．5±1．8到5．4±3．1,KCa通道电流被抑制约44％。电压依赖型钾通道抑制剂4-AP（四氨基吡啶）对大鼠前列腺上皮细胞膜钾电流有显著阻断效应。结论老年大鼠的前列腺上皮细胞膜钾通道电流比成年大鼠显著增强,同时老年大鼠KCa通道电流对TEA更敏感。由此结果可推论老年大鼠的前列腺上皮细胞分泌功能是降低的。

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.