Subtypes of purinoceptors in rat and dog urinary bladder smooth muscles

Open Access
Publisher Website
Google Scholar
Abstract
1 Both adenosine and adenosine 5′-triphosphate (ATP) (10 μm and 100 μm) relaxed 10 μm acetylcholine (ACh)-induced contraction of rat bladder strips, which was completely antagonized by 100 μm 8-(p-sulphophenyl) theophylline. In dog bladder neither adenosine nor ATP inhibited ACh-induced contraction. 2 P2x-purinoceptor agonists contracted both rat and dog bladder strips with the potency order of α,β-MeATP > ATP > ADP. 3 α,β-MeADP (100 μm) induced a contraction of the rat bladder strip even after desensitization of P2x-purinoceptors but failed to contract the dog bladder strip. 4 2-MeSATP (1 μm to 300 μm) concentration-dependently induced contraction of rat bladder strips; this contraction was significantly inhibited after desensitization of P2x-purinoceptors. Cibacron blue 3GA (100 μm) antagonized the drug at concentrations lower than 30 μm, whereas it augmented the response to the drug at concentrations above 30 μm. 5 ADPβS (1 μm to 1 mm) concentration-dependently induced contraction of rat bladder strips after desensitization of P2x-purinoceptors; a contraction which was significantly antagonized by cibacron blue 3GA (100 μm). 6 It is concluded that three subtypes of purinoceptors, P1 (mediating relaxation), and P2x and another type of P2 (mediating contraction), exist in rat urinary bladder smooth muscle, whereas a single subtype of the receptor, P2x-purinoceptor (mediating contraction) occurs in dog urinary bladder smooth muscle.

This publication has 23 references indexed in Scilit: