OBJECTIVETo investigate the impact of the BKCa channel in prostate smooth muscle cells (PSMCs) on the membrane potential in SD rats with chronic abacterial prostatitis (CAP).

METHODSCAP models were established in 20 SD rats by castration and injection of 17 beta-estrogen, and another 20 were taken as normal controls. PSMCs were cultured and purified in vitro, and treated with DiBAC4, followed by quantitative observations on the dynamic changes of the cell membrane potential by laser confocal microscopy.

RESULTSThe extracellular calcium ion concentration ([Ca2+]o) was increased and the BKCa channel was activated, which induced the hyperpolarization of the PSMC membrane in both the CAP models and normal control rats. This effect was weakened with Iberiotoxin (IbTX), a specific blocker of the BKCa channel, but the amplitude of the hyperpolarization was obviously lower in the CAP than in the control group. The DiBAC4 fluorescence intensity induced by hyperpolarization was 18.78 +/- 2.92 in the former and 38.85 +/- 7.10 in the latter (P < 0.05), while that induced by IbTX was 1.61 +/- 0.46 and 6.12 +/- 1.32 (P < 0.05), respectively.

CONCLUSIONSignificant decrease of BKCa-mediated hyperpolarization in the CAP model can reduce its abilities of regulating the membrane potential and suppressing the excessive contraction of PSMCs, which may result in pelvic pain syndrome and lower urinary tract symptoms.