Solomon L R
Department of Medicine, Veterans Administration Medical Center, West Haven, CT 06516.
Clin Chim Acta. 1988 Jul 29;175(3):249-65. doi: 10.1016/0009-8981(88)90101-5.
Since red cells transport and metabolize acetaldehyde in vivo, the effects of acetaldehyde on human red cell enzyme activities were studied. Incubation of intact red cells or undiluted red cell lysates at 37 degrees C for 4 h with 1-10 mmol/l acetaldehyde decreased only GOT, GPT and aldolase activities among the 26 enzymes tested. No inhibition occurred at 4 degrees C or when acetaldehyde was incubated with dilute hemolysates. Incubation of lysates with other reducing substrates or with acetate inhibited aldolase but not GOT or GPT. Preincubation of lysates with cyanate or fluoride markedly decreased acetaldehyde-mediated transaminase inhibition but not aldolase inhibition. Addition of pyridoxal phosphate, the vitamin B6 transaminase coenzyme, to GOT and GPT assay mixes did not reverse acetaldehyde-mediated transaminase inhibition. These findings suggest that acetaldehyde-mediated aldolase inhibition results from oxidation of acetaldehyde while transaminase inhibition results from nonoxidative acetaldehyde metabolism. When 100-200 mumol/l acetaldehyde is added to lysates at 2-h intervals and when lysates are incubated with ethanol, alcohol dehydrogenase and an NAD-regenerating system, enzyme inhibition occurs at acetaldehyde levels approaching those seen in vivo. Thus, the role of acetaldehyde-mediated enzyme inhibition in the toxicity of alcohol abuse warrants further study.
由于红细胞在体内运输和代谢乙醛，因此研究了乙醛对人红细胞酶活性的影响。在37℃下将完整红细胞或未稀释的红细胞裂解物与1 - 10 mmol/L乙醛孵育4小时，在所测试的26种酶中，仅降低了谷草转氨酶（GOT）、谷丙转氨酶（GPT）和醛缩酶的活性。在4℃下或乙醛与稀释的溶血产物孵育时未发生抑制作用。裂解物与其他还原底物或乙酸盐孵育可抑制醛缩酶，但不抑制GOT或GPT。裂解物与氰酸盐或氟化物预孵育可显著降低乙醛介导的转氨酶抑制作用，但不降低醛缩酶抑制作用。向GOT和GPT测定混合物中添加维生素B6转氨酶辅酶磷酸吡哆醛并不能逆转乙醛介导的转氨酶抑制作用。这些发现表明，乙醛介导的醛缩酶抑制作用是由乙醛氧化引起的，而转氨酶抑制作用是由非氧化的乙醛代谢引起的。当以2小时间隔向裂解物中添加100 - 200 μmol/L乙醛时，以及当裂解物与乙醇、乙醇脱氢酶和NAD再生系统孵育时，在乙醛水平接近体内所见水平时会发生酶抑制作用。因此，乙醛介导的酶抑制作用在酒精滥用毒性中的作用值得进一步研究。
