摘要
消炎痛作为一种可引起胃粘膜急性病变的药物，用分离提纯的猪胃Ｈ＋／Ｋ＋－ＡＴＰａｓｅ证明，它可以显著的抑制此酶的活力，０．１ｍｇ／ｍＬ时即可抑制酶活力２７％，０．５ｍｇ／ｍＬ时可抑制全部活力，其Ｋ（０．５）为０．１８ｍｇ／ｍＬ。消炎痛对Ｈ＋／Ｋ＋－ＡＴＰａｓｅ的抑制随３０℃时预保温时间的延长而加剧，１０ｍｉｎ预保温可抑制总活力的５０％。消炎痛并不影响Ｈ＋／Ｋ＋－ＴＡＰａｓｅ的转换温度（３９℃）以及最适ｐＨ（约ｐＨ７．５），但酸性条件下消炎痛对Ｈ＋／Ｋ＋－ＡＴＰａｓｅ抑制比碱性条件下强烈。在我们的实验条件下，消炎痛对Ｈ＋／Ｋ＋－ＡＴＰａｓｅ的抑制与Ｈ＋／Ｋ＋－ＡＴＰａｓｅ量成正比，它不影响酶的Ｋｍ值（０．１１ｍｍｏｌ／Ｌ），而是显著降低Ｖｍａｘ，因而它是此酶的可逆性非竞争性抑制剂，其Ｋｉ为０．３２ｍｍｏｌ／Ｌ。
It had been shown from the results of our laboratory that indomethacin could induce the acute mucosal lesion of rats, with inactivation of acid transportation of H+/K+-ATPase in vivo. In this paper, we investigated the effect of indomethacin on the kinetic properties of the enzyme,in vitro. Indomethacin inhibited the activity of H+/K+-ATPase significantly (27%) at a concentration as low as 0. 1mg/mL, and it caused full inhibition (100%) at the concentration of 0.5mg/mL with an apparent K0.5=0.18mg/mL. When H+/K+-ATPase was preincubated with indomethacin at 30℃, the hydrolysis of ATP by the enzyme was inhibited increasingly with the incubation time. The degree of inhibition produced by indomethacin was found to be dependent on pH and temperature remarkably. The higher the pH, the less the inhibition. The inhibition rate in pH8. 5 was only 46 percent of that in pH6. 5. But it did not change the reversion temperature of H+/K+-ATPase(39℃). At a definite concentration of indomethacin the rate of ATP hydrolysis was linearly related to the concentration of the enzyme, showing that the inhibition of indomethacin was reversible. Under our experimental conditions, the pig gastric H+/K+-ATPase showed simple Michaelis-Menten type kinetics. The apparent Km was about 0. 11mmol/L, with Vmax at 82. 6μmol pi/mg/hr. The inhibition of 0. 2mg/mL indomethacin gave out the same apparent Km but olwer Vmax (about 50. 7% of control), which showed that indomethacin is a noncompetitive inhibition of H+/K+-ATPase with Ki about 0. 32mmol/L.
基金
国家自然科学基金
关键词
消炎痛
胃
氢
钾
腺苷三磷酸
Pig gastric H￣+/K￣+-ATPase
Inhibition
Indomethacin
