Article date: May 1994
By: Hideka Suzuki, Shinichiro Kokubun, in Volume 112, Issue 1, pages 117-122
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.
P2x‐purinoceptor agonists contracted both rat and dog bladder strips with the potency order of α,β‐MeATP > ATP > ADP.
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.
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.
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).
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.
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.
P2x‐purinoceptor agonists contracted both rat and dog bladder strips with the potency order of α,β‐MeATP > ATP > ADP.
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.
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.
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).
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.
DOI: 10.1111/j.1476-5381.1994.tb13039.x
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