title: Activation of the nitric oxide-cGMP pathway reduces phasic contractions in neonatal rat bladder strips via protein kinase G.
abstract: Nitric oxide (NO), a neurotransmitter in the lower urinary tract, stimulates soluble guanylyl cyclase (sGC) and in turn cGMP-dependent protein kinase G (PKG) to modulate a number of downstream targets. NO donors reduce bladder hyperactivity in some pathological models but do not affect normal bladder activity in the adult rat. In this study, the NO donor S-nitroso-N-acetyl-DL-penicillamine (SNAP; 100 microM) decreased the amplitude and frequency of spontaneous and carbachol-enhanced contractions in neonatal rat bladder strips, which are intrinsically hyperactive. This effect was blocked by inhibition of sGC and mimicked by application of a membrane-permeable cGMP analog (8-bromo-cGMP, 100 microM). Inhibition of PKG prevented or reversed the inhibitory effects of 8-bromo-cGMP. A portion of the SNAP-mediated inhibition was also dependent upon PKG; however, a short-lasting, sGC-dependent inhibitory effect of SNAP was still present after PKG inhibition. Inhibition of NO synthase with L-NAME (100 microM) did not change the amplitude or frequency of contractions. However, inhibition of endogenous phosphodiesterase (PDE)-5 with zaprinast (25 microM) reduced the amplitude and frequency of phasic contractions and increased the magnitude of inhibition produced by maximal concentrations of SNAP, suggesting that endogenous PDEs are constitutively active and regulate cGMP production. These results suggest that the NO-cGMP-PKG pathway may be involved in inhibitory control of the neonatal rat bladder.
authors.affiliation: Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA. dea20@pitt.edu
authors.forename: Debra E
authors.initials: DE
authors.lastname: Artim
authors.forename: F Aura
authors.initials: FA
authors.lastname: Kullmann
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Daugherty
authors.forename: Hsi-Yang
authors.initials: HY
authors.lastname: Wu
authors.forename: William C
authors.initials: WC
authors.lastname: de Groat
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism*; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5 / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D006162:Guanylate Cyclase / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000201:enzymology* / Q000294:innervation; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009433:Neural Inhibition; D026602:Nitrergic Neurons / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000378:metabolism; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011688:Purinones / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D001743:Urinary Bladder / Q000187:drug effects / Q000201:enzymology* / Q000294:innervation
chemical_list: D018679:Cholinergic Agonists; D020030:Nitric Oxide Donors; D010726:Phosphodiesterase Inhibitors; D047428:Protein Kinase Inhibitors; D011688:Purinones; C016276:8-bromocyclic GMP; D009569:Nitric Oxide; D026423:S-Nitroso-N-Acetylpenicillamine; D002217:Carbachol; D019001:Nitric Oxide Synthase; D017869:Cyclic GMP-Dependent Protein Kinases; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D006162:Guanylate Cyclase; C011145:zaprinast; D006152:Cyclic GMP; D019331:NG-Nitroarginine Methyl Ester