Kidney transaminase activities

While considerable amounts of both GOT and GPT are found in cardiac muscle, skeletal muscle and kidney, differential diagnosis is aided by the fact that the liver shows a much higher total GPT activity. An important clinical application of measurements of transaminase activity is the detection and diagnosis of viral... 

Apart from hormonal aspects of pseudocholinesterase activity previously dealt with (48,86,107), there have been a number of studies since 1954 showing that cortisone may act on the transaminase activity of various organs (46, 49, 103), particularly liver, heart, and kidneys, which have the highest activity (4,21). In 1957 Gavosto et al. (58) suggested that the hormone may enhance gluconeogenesis by activating the transamination process in the liver. Rosen et al. (104-106) found... 

Induction of extrahepatic mdoleamine dioxygenase (which catalyzes the same reaction as tryptophan dioxygenase, albeit by a different mechanism) by bacterial lipopolysaccharides and mterferon-y may result in the production of relatively large amounts of kynurenine and hydroxykynurenine in tissues that lack the enzymes for onward metabolism. Kidney has kynurenine transaminase activity, and therefore extrahepatic metabolism of tryptophan may result in significant excretion of kynurenic and xanthurenic acids, even when vitamin Bg nutrition is adequate. 

In 25 children with chronic hepatitis C, pretreatment positivity for liver/kidney microsomal type 1 (LKM-1) antibodies was associated with more frequent treatment-limiting increases in serum alanine transaminase activity (256). Withdrawal of interferon alfa-2b because of hypertransaminasemia was required in three of four LKM-1 positive children compared with two of the 21 LKM-1 negative children. Although none developed features of autoimmune hepatitis, careful surveillance of hepatic function is recommended in LKM-l-positive patients. 

In mice intraperitoneally administered 15 mg/kg of usnic acid daily for 15 days, elevated levels of serum transaminase activity and extensive liver necrosis were observed. No signs of toxicity in other organs, such as the kidney or spleen, were detected. A similar pattern of toxicity was revealed in tumor-bearing mice (da Silva Santos et al. 2006 Ribeiro-Costa et al. 2004). 

Injection of hydrocortisone into the rat results in an approximately four fold increase in liver (but not kidney) tyrosine-a-ketoglutarate transaminase activity 374)- Corticosterone and cortisone were somewhat less effective. Interesting in this connection is the observation that injection of L-tyrosine increased the activity of tyrosine-a-ketoglutarate transaminase to about the same extent as hydrocortisone. Other amino acids had a much smaller stimulating effect which was attributed to adrenal cortical stress. In a preliminary report the addition of hydrocortisone to lymphocyte suspensions was found to inhibit glutamic-oxalacetic transaminase activity 376). 

Transamination reactions combine reversible amina-tion and deamination, and they mediate redistribution of amino groups among amino acids. Transaminases (aminotransferases) are widely distributed in human tissues and are particularly active in heart muscle, liver, skeletal muscle, and kidney. The general reaction of transamination is... 

Studies in vitro with rat kidney tissue preparations showed that estrogen sulfates inhibit kynurenine transaminase in a reversible fashion that can be relieved by dialysis (MIO, Mil). Competition of sulfate and phosphate esters of estrogens with PLP for the kynurenine transaminase apoenzyme has been demonstrated (S5). An estrogen effect on this enzyme in vivo was suggested by the finding of higher enzyme activity in the kidneys of adult male rats than in either females or estrogen-treated males (M9, Mil). This difference applied to renal kynurenine transaminase, two-thirds of which is in the soluble fraction and the... 

Determination of ALT ALT (formerly glutamate pyruvate transaminase) catalyzes the equilibrium transfer reaction of the amino group from L-alanine to 2-oxoglutarate to form L-glutamate and pyruvate ALT requires pyridoxal phosphate as coenzyme, which acts as an amino carrier. It is found in the main organs, such as the liver, kidney, and heart. The ALT activity in serum is elevated in diseases of the liver. 

---