Both adenosine and adenosine 5'-triphosphate (ATP) (10 microM and 100 microM) relaxed 10 microM acetylcholine (ACh)-induced contraction of rat bladder strips, which was completely antagonized by 100 microM 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 alpha,beta-MeATP > ATP > ADP. 3. Alpha,beta-MeADP (100 microM) 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 microM to 300 microM) concentration-dependently induced contraction of rat bladder strips; this contraction was significantly inhibited after desensitization of P2x-purinoceptors. Cibacron blue 3GA (100 microM) antagonized the drug at concentrations lower than 30 microM, whereas it augmented the response to the drug at concentrations above 30 microM. 5. ADP beta S (1 microM 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 microM). 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.
摘要
腺苷和5'-三磷酸腺苷（ATP）（10微摩尔和100微摩尔）均可舒张10微摩尔乙酰胆碱（ACh）诱导的大鼠膀胱条收缩，而100微摩尔8-（对-磺基苯基）茶碱可完全拮抗这种舒张作用。在犬膀胱中，腺苷和ATP均不能抑制ACh诱导的收缩。2. P2x嘌呤受体激动剂可使大鼠和犬的膀胱条收缩，其效力顺序为α,β-亚甲基ATP＞ATP＞ADP。3. 即使在P2x嘌呤受体脱敏后，α,β-亚甲基ADP（100微摩尔）仍可诱导大鼠膀胱条收缩，但不能使犬膀胱条收缩。4. 2-甲硫基ATP（1微摩尔至300微摩尔）浓度依赖性地诱导大鼠膀胱条收缩；在P2x嘌呤受体脱敏后，这种收缩明显受到抑制。Cibacron blue 3GA（100微摩尔）在浓度低于30微摩尔时可拮抗该药物，而在浓度高于30微摩尔时可增强对该药物的反应。5. 在P2x嘌呤受体脱敏后，ADPβS（1微摩尔至1毫摩尔）浓度依赖性地诱导大鼠膀胱条收缩；这种收缩可被100微摩尔Cibacron blue 3GA明显拮抗。6. 由此得出结论，大鼠膀胱平滑肌中存在三种嘌呤受体亚型，即P1（介导舒张）、P2x和另一种P2（介导收缩），而犬膀胱平滑肌中仅存在一种受体亚型，即P2x嘌呤受体（介导收缩）。
