Westfall T D, Sarkar S, Ramphir N, Westfall D P, Sneddon P, Kennedy C
Department of Physiology and Pharmacology, University of Strathclyde, Strathclyde Institute for Biomedical Sciences, 27 Taylor Street, Glasgow G4 0NR.
Br J Pharmacol. 2000 Apr;129(8):1684-8. doi: 10.1038/sj.bjp.0703271.
The release of ATPase activity evoked by electrical field stimulation (EFS) (8 Hz, 25 s) was investigated in several tissues in which adenosine 5'-triphosphate (ATP) acts as a neurotransmitter. Superfusate collected during EFS of sympathetic nerves of the guinea-pig, rat and mouse isolated vas deferens and parasympathetic nerves of the guinea-pig isolated urinary bladder contained ATPase activity. ATP breakdown was fastest in superfusate collected from the guinea-pig isolated vas deferens. However, EFS of the enteric nerves of the guinea-pig isolated taenia coli did not release any detectable ATPase. The ATPase released from the guinea-pig isolated vas deferens metabolized ATP at similar rates at incubation temperatures of 37 degrees C and 20 degrees C. Lineweaver-Burke analysis of the initial rates of ATP hydrolysis gave a K(M) of 39 microM and a V(max) of 1039 pmol ATP metabolized min(-1) ml(-1) superfusate. 6-N,N-diethyl-D-beta,gamma-dibromomethyleneATP (ARL 67156), pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) and pyridoxal-5'-phosphate (P-5-P) all inhibited the ATPase activity in a concentration-dependent manner with a potency order of ARL 67156 = PPADS>P-5-P. In conclusion, EFS of several tissues in which ATP is a neurotransmitter causes the release of an ATPase and activity is greatest in the guinea-pig vas deferens. The enzyme has pharmacological and kinetic characteristics that are similar to ectonucleoside triphosphate diphosphohydrolases.
在几种以5'-三磷酸腺苷（ATP）作为神经递质的组织中，研究了电场刺激（EFS）（8Hz，25s）诱发的ATP酶活性释放情况。在豚鼠、大鼠和小鼠离体输精管的交感神经以及豚鼠离体膀胱的副交感神经进行EFS期间收集的超滤液中含有ATP酶活性。从豚鼠离体输精管收集的超滤液中ATP分解最快。然而，豚鼠离体结肠带肠神经的EFS并未释放出任何可检测到的ATP酶。从豚鼠离体输精管释放的ATP酶在37℃和20℃的孵育温度下以相似的速率代谢ATP。对ATP水解初始速率进行Lineweaver-Burke分析得出，米氏常数（K(M)）为39μM，最大反应速度（V(max)）为1039pmol ATP代谢·min⁻¹·ml⁻¹超滤液。6-N,N-二乙基-D-β,γ-二溴亚甲基ATP（ARL 67156）、磷酸吡哆醛-6-偶氮苯基-2',4'-二磺酸（PPADS）和磷酸吡哆醛-5'-磷酸（P-5-P）均以浓度依赖性方式抑制ATP酶活性，其效力顺序为ARL 67156 = PPADS > P-5-P。总之，在几种以ATP作为神经递质的组织中，EFS会导致ATP酶的释放，且在豚鼠输精管中活性最高。该酶具有与胞外核苷三磷酸二磷酸水解酶相似的药理学和动力学特征。
