Rat urinary bladder-derived relaxant factor: studies on its nature and release by coaxial bioassay system.
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.
Bozkurt
Turgut Emrah
TE
Hacettepe University, Faculty of Pharmacy, Department of Pharmacology, 06100, Sihhiye, Ankara, Turkey.
Sahin-Erdemli
Inci
I
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*
D018048:Receptors, Purinergic P2; D017868:Cyclic AMP-Dependent Protein Kinases; D000262:Adenylyl Cyclases; D000109:Acetylcholine