BACKGROUND Prostatic stromal cells are believed to be a key factor in the pathogenesis of benign prostatic hyperplasia (BPH). The effect of phenylephrine, an α1‐adrenergic receptor agonist, and doxazosin, an α1‐adrenergic receptor‐specific antagonist, on the expression of smooth muscle myosin‐heavy‐chain isotypes SM‐1 and SM‐2 was tested in an in vitro model of prostatic smooth muscle cells (SMC). METHODS Primary prostatic stromal cells, grown in SMC‐specific medium, were treated with 10 μM of phenylephrine or 1 μM of doxazosin or a combination of both. SM‐2 to SM‐1 mRNA ratios and expression of α1‐adrenergic receptor subtypes were determined by means of reverse transcriptase polymerase chain reaction (RT‐PCR) techniques. Cell growth was measured by a cell viability assay. RESULTS SM‐1 mRNA and only very low levels of SM‐2 mRNA were detected in prostatic SMC cultures grown for 4 days in a serum‐free base medium. After 6 days of treatment, SM‐2 expression increased, highest in the doxazosin‐treated cultures. In comparison to unstimulated cells, a statistically significant 10‐fold increase of the SM‐2:SM‐1 ratio was measured in doxazosin‐treated cultures. Analysis of α1‐adrenergic receptor subtype expression revealed the presence of mRNAs of subtypes 1d and 1b mRNAs. Subtype 1a was not expressed. Phenylephrine and doxazosin showed no significant effect on cell proliferation and on α1d‐adrenergic receptor expression. CONCLUSIONS SMC can differentiate from a proliferative to a contractile phenotype, which is accompanied by increased expression of isotope 2 of smooth muscle myosin heavy chain. Our results suggest that doxazosin seems to have a long‐term effect on the differentiation of prostatic stromal cells, indicating that α1‐adrenergic receptor antagonists do not act solely on SMC contractility. Prostate 39:226–233, 1999. © 1999 Wiley‐Liss, Inc.

BACKGROUND α1‐adrenoceptor (α1‐AR) antagonists, used to relieve the lower tract urinary symptoms (LUTS) in benign prostate hyperplasia (BPH) patients, are thought to act in inhibiting the contraction of stromal smooth muscle. An attempt was made using new technology to visualize and quantify the effect of α1‐AR antagonists in a cell culture model of prostatic smooth muscle cells (SMC). METHODS Prostatic smooth muscle cells cultured from human prostate tissue were treated with α1‐AR agonists and antagonists. The effects on cell growth, cell contraction, differentiation status, and apoptosis were determined by means of an MTT cell viability assay, time‐lapse video microscopy, RT‐PCR analysis, and FACS analysis of annexin V/propidium iodide‐stained cells, respectively. RESULTS Prostatic smooth muscle cells derived from prostate tissue expressed SMC‐specific markers. They showed spontaneous contractions, and phenylephrine increased the percentage of contracting cells by 3‐fold. α1‐AR antagonists inhibited spontaneous as well as phenylephrine‐induced contractions. Long‐term treatment with doxazosin induced differentiation tended towards a contractile phenotype, as indicated by an increase of the ratio of smooth muscle heavy chain myosin subtypes SM2/SM1. There was, however, no effect on cell growth. High concentrations of antagonist (100 μM) induced apoptosis in about 80% of the treated SMC. This effect was not cell‐type‐specific and was also seen in skin fibroblasts and immortalized prostate epithelial cells. CONCLUSION In an easy‐to‐handle cell culture model of prostatic smooth muscle cells, the effects of α1‐AR antagonists on cell contraction, growth, and differentiation can be investigated. The results indicate that in addition to inhibition of cell contraction, α1‐AR antagonists have the potential to induce apoptosis. Prostate Supplement 9:34–41, 2000. © 2000 Wiley‐Liss, Inc.

These results demonstrate that cholinergic stimulation triggers contraction of cultured human rhabdosphincter cells. This model might help to understand external urethral sphincter physiology and to establish new therapies for the treatment of sphincter dysfunctions. Prostate 47:189-193, 2001.

Objectives: Different thermotherapeutic modalities such as transurethral microwave therapy or transurethral needle ablation have been developed to provide effective alternatives to surgical management of benign prostate hyperplasia (BPH). The mechanisms of thermotherapy, however, are not completely understood. We developed a model to investigate the effects of heat application on stromal cell viability and contractility.Methods: Cells isolated from prostatectomy and cystoprostatectomy specimens were cultured in a selective medium. Temperatures ranging from 37 to 50°C were applied for 1 h. Cell contraction was visualized by means of a cell culture microscope equipped with a time–lapse video system. For quantitative analysis, the percentage of contracting cells was evaluated; 10 μM of phenylephrine were applied for adrenergic stimulation of the cells.Results: On immunohistochemistry and phase–contrast microscopy, these cells were identified as prostatic myofibroblasts. Incubation at 50°C for 1 h in vitro induced immediate death of all cells, whereas at 45°C all cells survived. At 37°C 55% of the cells were seen to contract after addition of phenylephrine. Immediately after incubation at 45°C contraction rate decreased to 29%, but returned to 46% 1 day later.Conclusions: With this model, it is possible to study the mechanisms of thermotherapy in vitro. The results suggest that the effects of thermotherapy are due to the induction of cell death rather than to reduced stromal cell contractility. Furthermore, the data show that treatment is probably only successful if temperatures in excess of 50°C are maintained.

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