CHARACTERIZATION OF MUSCARINIC CHOLINOCEPTOR IN PRIMARY CULTURE OF SMOOTH-MUSCLE CELLS FROM HUMAN PROSTATE

We obtained a primary culture of prostatic cells by an explant method from patients with benign prostatic hypertrophy (BPH). Ultrastructural morphology and growth characteristics of these cells conformed to tho se reported for smooth muscle cells isolated from vascular and viscera l tissue sources. The cells retained their original character includin g the presence of androgen receptor, acid phosphatase and normal chrom osomal number. [H-3]-methyl-quinuclidinyl benzilate (QNB) saturation e xperiments showed the existence of a homogeneous population of binding sites with a high affinity and low capacity (K-D = 0.17 +/- 0.05 nM., B-max = 15,000 sites per cell). inhibition of [H-3]-methyl-QNB bindin g by nonlabelled compounds showed these [H-3]methyl-QNB binding sites to be M(2) muscarinic cholinoceptors. cAMP formation induced by forsko lin and isoproterenol was inhibited by carbamoyl choline and oxotremor ine. These results suggest that prostatic smooth muscle cells contain M(2) muscarinic cholinoceptors and that these cholinoceptors couple ad enylate cyclase inhibition.