title: Protein kinase G activation of K(ATP) channels in human-cultured prostatic stromal cells.
abstract: In this study, we identify and investigate the role of protein kinase G (PKG) in cells cultured from human prostatic stroma. Cells were used for immunocytochemistry, contractility or K(+) fluorescent imaging studies. All cultured prostatic stromal cells showed PKG immunostaining. Phorbol 12,13 diacetate (PDA, 1 microM) elicited contractions from human-cultured prostatic stromal cells that could be blocked by both the L-type Ca(2+) channel blocker, nifedipine (3 microM), and the protein kinase C inhibitor, bisindolylmaleimide (1 microM). The nitric oxide donor, sodium nitroprusside (SNP, molar pIC(50) 5.16+/-0.17) and the cGMP-phosphodiesterase inhibitor, zaprinast (50 microM), inhibited PDA (1 microM)-induced contractions. The PKG activator beta-phenyl-1, N(2)-ethenoguanosine-3',5'-cyclic monophosphate (PET-cGMP, molar pIC(50) 6.96 +/- 0.25) also inhibited PDA (1 microM)-induced contractions. Glibenclamide (10 microM) and Rp-8-Br-cGMPS (5 microM), but not iberiotoxin (100 nM) or Rp-cAMP (5 microM), reversed this inhibition. In human-cultured prostatic stromal cells loaded with the K(+) fluorescent indicator, 1,3-Benzenedicarboxylic acid, 4,4'-[1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7,16-diylbis(5-methoxy-6,2-benzofurandiyl)]bis-, tetrakis [(acetyloxy) methyl] ester (PBFI), PET-cGMP (300 nM) caused a reduction in intracellular K(+) that was blocked by glibenclamide (10 microM) and Rp-8-Br-cGMPS (5 microM), but not by iberiotoxin (100 nM). These data are consistent with the hypothesis that, in human-cultured prostatic stromal cells, PKG inhibits contractility through the activation of K(ATP) channels.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000368:Aged; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000502:physiology; D002478:Cells, Cultured; D017869:Cyclic GMP-Dependent Protein Kinases / Q000032:analysis / Q000276:immunology / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009119:Muscle Contraction; D010703:Phorbol Esters / Q000494:pharmacology; D011188:Potassium / Q000032:analysis; D015221:Potassium Channels / Q000378:metabolism*; D011467:Prostate / Q000166:cytology*; D011493:Protein Kinase C / Q000502:physiology; D017154:Stromal Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*
chemical_list: D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D010703:Phorbol Esters; D015221:Potassium Channels; C008874:phorbol-12,13-diacetate; D000255:Adenosine Triphosphate; D017869:Cyclic GMP-Dependent Protein Kinases; D011493:Protein Kinase C; D011188:Potassium