title: Rat urinary bladder-derived relaxant factor: studies on its nature and release by coaxial bioassay system.
abstract: The present study was designed to characterize the urinary bladder-derived relaxant factor that was demonstrated by acetylcholine-induced relaxation response in a coaxial bioassay system consisting of rat bladder as the donor organ and rat anococcygeus muscle as the assay tissue. The concentration-dependent relaxation to acetylcholine (10 nM-1 mM) was inhibited by atropine but was not altered by the antagonists of calcitonin gene-related peptide (CGRP 8-37), vasoactive intestinal peptide (VIP 6-28), tachykinin NK1 (L-732138), tachykinin NK2 (MEN-10376), tachykinin NK3 (SB-218795), purinergic P2 (PPADS) and adenosine (CGS 15943) receptors as well as alpha-chymotrypsin. Adenylate cyclase inhibitor SQ-22536 and protein kinase A inhibitor KT-5720 significantly inhibited the acetylcholine response while guanylate cyclase inhibitor ODQ, and protein kinase C inhibitor H-7 did not have any effect. The P2X agonist alpha,beta-methylene ATP (10 nM-0.1 mM) also produced concentration-dependent relaxation response that was inhibited by PPADS, SQ-22536 and KT-5720 in the coaxial bioassay system. In bladder strips, acetylcholine and alpha,beta-methylene ATP elicited concentration-dependent contractions that were not altered in the presence of SQ-22536 and KT-5720. In conclusion, the urinary bladder-derived relaxant factor that was recognized by the coaxial bioassay system is neither a peptide of the bladder neurons nor a purinergic mediator but adenylate cyclase and protein kinase A are involved in its release and/or relaxant effect. Furthermore, activation of purinergic P2X receptors besides the muscarinic receptors leads to the release of this factor.
authors.affiliation: Hacettepe University, Faculty of Pharmacy, Department of Pharmacology, 06100, Sihhiye, Ankara, Turkey.
authors.forename: Turgut Emrah
authors.initials: TE
authors.lastname: Bozkurt
authors.forename: Inci
authors.initials: I
authors.lastname: Sahin-Erdemli
mesh_terms: D000109:Acetylcholine / Q000008:administration & dosage / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001681:Biological Assay / Q000379:methods*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D001743:Urinary Bladder / Q000187:drug effects / Q000378:metabolism*
chemical_list: D018048:Receptors, Purinergic P2; D017868:Cyclic AMP-Dependent Protein Kinases; D000262:Adenylyl Cyclases; D000109:Acetylcholine