title: Constitutively active PKA regulates neuronal acetylcholine release and contractility of guinea pig urinary bladder smooth muscle.
abstract: Autonomic and somatic motor neurons that innervate the urinary bladder and urethra control the highly coordinated functions of the lower urinary tract, the storage, and the emptying of urine. ACh is the primary excitatory neurotransmitter in the bladder. Here, we aimed to determine whether PKA regulates neuronal ACh release and related nerve-evoked detrusor smooth muscle (DSM) contractions in the guinea pig urinary bladder. Isometric DSM tension recordings were used to measure spontaneous phasic and electrical field stimulation (EFS)- and carbachol-induced DSM contractions with a combination of pharmacological tools. The colorimetric method was used to measure ACh released by the parasympathetic nerves in DSM isolated strips. The pharmacological inhibition of PKA with H-89 (10 μM) increased the spontaneous phasic contractions, whereas it attenuated the EFS-induced DSM contractions. Intriguingly, H-89 (10 μM) attenuated the (primary) cholinergic component, whereas it simultaneously increased the (secondary) purinergic component of the nerve-evoked contractions in DSM isolated strips. The acetylcholinesterase inhibitor, eserine (10 μM), increased EFS-induced DSM contractions, and the subsequent addition of H-89 attenuated the contractions. H-89 (10 μM) significantly increased DSM phasic contractions induced by the cholinergic agonist carbachol. The inhibition of PKA decreased the neuronal release of ACh in DSM tissues. This study revealed that PKA-mediated signaling pathways differentially regulate nerve-evoked and spontaneous phasic contractions of guinea pig DSM. Constitutively active PKA in the bladder nerves controls synaptic ACh release, thus regulating the nerve-evoked DSM contractions, whereas PKA in DSM cells controls the spontaneous phasic contractility.
authors.affiliation: Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina.
authors.forename: Wenkuan
authors.initials: W
authors.lastname: Xin
authors.affiliation: Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina.
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.affiliation: Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina.
authors.forename: Vitor S
authors.initials: VS
authors.lastname: Fernandes
authors.affiliation: Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina petkov@cop.sc.edu.
authors.forename: Georgi V
authors.initials: GV
authors.lastname: Petkov
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004558:Electric Stimulation; D006168:Guinea Pigs; D007546:Isoquinolines / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010830:Physostigmine / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D001743:Urinary Bladder / Q000187:drug effects / Q000378:metabolism*
chemical_list: D018679:Cholinergic Agonists; D002800:Cholinesterase Inhibitors; D007546:Isoquinolines; D047428:Protein Kinase Inhibitors; D013449:Sulfonamides; D002217:Carbachol; D010830:Physostigmine; D017868:Cyclic AMP-Dependent Protein Kinases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; D000109:Acetylcholine
keywords: H-89; acetylcholine; detrusor smooth muscle; muscarinic receptor; protein kinase A