Aims: Prostate stromal cell cultures are used in vitro to study the cellular pathophysiology of benign prostatic hyperplasia (BPH), but their functional properties are poorly understood. This study characterized intracellular Ca2+ ([Ca2+]i) regulation in a cultured cell line in comparison to freshly isolated cells, as a background to understanding contractile regulation and cellular proliferation in this tissue.
Methods: Prostate stromal cells were isolated from either PrS6 cell cultures, with an extended life span by transfection with the SV40 T-antigen, tsA58-U19, or freshly obtained transition zone prostate samples, primary cells. [Ca2+]i was measured in vitro with the indicator Fura-2 by epifluorescence microscopy.
Results: Phenylephrine, high-K+, and caffeine induced Ca2+-transients in primary cells (resting [Ca2+]i 94 +/- 8 nM, n = 29; peak 193 +/- 26 nM, n = 19). In PrS6 cells resting [Ca2+]i was 96 +/- 8 nM (n = 78) and in 34 of these 78 cells, 30 microM phenylephrine increased [Ca2+]i to 296 +/- 28 nM. 5-methyl-urapidil (10-30 microM) inhibited this response in 10 of 16 cells. Spontaneous Ca2+-transients were also observed in 91% of phenylephrine-responsive cells, but in only 20% of non-responsive cells (P < 0.01). Ca2+-transients were also induced by high-K+ solution, and 20 mM caffeine. The latter abolished the response to subsequent phenylephrine application. Depletion of intracellular Ca2+ stores by caffeine or restoration from a Ca2+-free superfusate caused a substantial rise of [Ca2+]i.
Conclusions: PrS6 prostate stromal cells express functional alpha1-adrenoceptors associated with spontaneous intracellular Ca2+-transients. They exhibit functional Ca2+ channels, intracellular Ca2+ stores, and Ca2+ entry induced by store depletion. Stromal cultures can therefore be used to characterize the cellular physiology of prostate stromal cell contraction and proliferation.