Fumio Okuno

Hepatic and intestinal gamma-glutamyltranspeptidase activity: Its activation by chronic ethanol administration

Abstract To study the effect of chronic ethanol administration on the activity of gamma-glutamyltranspeptidase (GGTP) in various tissues, female rats were pair-fed liquid diets with 36% of total calories either as ethanol or isocaloric carbohydrate (controls). Six weeks of ethanol feeding in an increase of cytochrome P450 content by 70%. Hepatic microsomal GGTP activity was more than doubled after ethanol feeding whether expressed per gram of liver or per mg of microsomal protein. Furthermore intestinal GGTP activity was significantly enhanced after ethanol, whereas there was no change in the enzyme activity in either kidney or pancreas. Phenobarbital administration to rats also resulted in an enahancement of GGTP activity in the liver but not in the intestine. These results suggest that enhanced hepatic and intestinal GGTP activities may contribute, at least partly, to increased serum GGTP activity frequently seen in alcoholics.

Effect of interleukin 1 (IL-1) on the levels of cytochrome P-450 involving IL-1 receptor on the isolated hepatocytes of rat

In the present study, the expression of IL-1 receptor (IL-1 R) on the primary cultured hepatocytes was determined and the effect of IL-1 on the intracellular amount of cytochrome P-450 was investigated. The kinetics of IL-1R on the hepatocytes was studied by [125I]-IL-1 alpha and revealed that 5,000 molecules of IL-1 bound to a hepatocyte with a Kd of 4.0 x 10(-9) M. Incubation of the hepatocytes with IL-1 for 18 hrs decreased the contents of cytochrome P-450 in a dose-dependent manner. These findings suggest that IL-1 potentially depresses the drug metabolism involving IL-1R which is expressed on hepatocytes.

Potentiation of halothane hepatotoxicity by chronic ethanol administration in rat: An animal model of halothane hepatitis

To determine if chronic ethanol administration modifies the effect of halothane on the liver, fourteen male Wistar rats were pair-fed nutritionally adequate liquid diets containing either ethanol (36% of calories) or isocaloric carbohydrate (controls) for 6 weeks. After halothane anesthesia of these animals under different oxygen concentration, the livers were examined light microscopically as well as biochemically. The livers from rats fed ethanol which received halothane at low oxygen concentration showed multifocal or patchy necrosis primarily in the centrilobular regions with parenchymal lipid accumulation, whereas no such lesions were not observed in pair-fed controls. Hepatic necrosis was also seen after halothane anesthesia even at ambient oxygen concentrations, although the degree of necrosis was much milder. Hepatic microsomal cytochrome P450 content was increased by 30% after ethanol but was decreased following halothane anesthesia. These data suggest that halothane is hepatotoxic to liver of rats chronically pretreated with ethanol, especially under hypoxic condition.

Significance of serum gamma glutamyl transpeptidase as a marker of alcoholism

To study the effect of chronic ethanol administration on the activity of gamma glutamyl transpeptidase (GGTP) in various tissues, female rats were pair-fed liquid diets with 36% of total calories either as ethanol or as isocaloric carbohydrate (controls). Six weeks of ethanol feeding resulted in a significant increase of cytochrome P450 content. Hepatic microsomal GGTP activity was almost doubled after ethanol feeding whether expressed per g of liver or per mg of microsomal protein. Furthermore, intestinal GGTP activity was significantly enhanced after ethanol, whereas there was no change in the enzyme activity in either kidney or pancreas. There was a concomitant elevation of plasma GGTP activity. Phenobarbital administration to rats resulted in an enhancement of GGTP activity in the liver whether given orally or intraperitoneally. In addition, intestinal GGTP activity after oral phenobarbital was also significantly increased, although its activity after intraperitoneal administration was not enhanced. These results suggest that enhanced hepatic and intestinal GGTP activities may contribute, at least in part, to an increased level of serum GGTP frequently seen in chronic alcoholics.

Increase in mitochondrial GOT (m-GOT) activity after chronic alcohol consumption: clinical and experimental observations

In order to clarify the origin and the mechanism of increased serum activity of glutamic oxalacetic transaminase (GOT) in chronic alcoholics, clinical and experimental investigations were carried out. Mitochondrial (m-GOT) and cytosolic GOT (c-GOT) isoenzymes were separated chromatographically by using a mini-column packed with Sephadex A50. Sixty percent of 63 alcoholics had elevated serum GOT. The m-GOT activity in alcoholics with total serum GOT activity of over 50 Karmen Units was 17.2 +/- 1.6 K.U. and the m-GOT/GOT ratio was the highest when compared to those in non-alcoholic liver diseases. In in vitro study, six hours of incubation of isolated hepatocytes from rats fed ethanol chronically resulted in an increased leakage of m-GOT into the incubation medium and also showed a tendency of a higher m-GOT/GOT ratio than that from control rats. The m-GOT activity thus released into the medium showed a highly significant inverse correlation with the viability of hepatocytes. These data suggest that m-GOT substantially contributes to an increased serum GOT often observed in chronic alcoholics.

Mild but prolonged elevation of serum angiotensin converting enzyme (ACE) activity in alcoholics

Serum activity of angiotensin converting enzyme (ACE) was serially measured in 47 hospitalized chronic alcoholics with liver disease. Compared to healthy controls, ACE activity, on admission, in the serum of alcoholics was significantly elevated (42.5 +/- 16.6 U/ml vs. 32.4 +/- 9.6 U/ml; p less than 0.005). About 36% of the patients had an elevated ACE level exceeding an upper normal value of 42 U/ml (mean +/- SD). In contrast to the rapid normalization of such enzymes as aspartate transaminase (AST), alanine transaminase (ALT) and lactic dehydrogenase (LDH) which represent parenchymal liver cell injury, the activity of ACE remained elevated over a period of 4 weeks even with abstinence. The serum level of ACE was significantly correlated with levels of alkaline phosphatase, gamma-glutamyltranspeptidase and monoamine oxidase, but not with those of AST, ALT and LDH. These data suggest increased ACE activity in alcoholics may be related to the influence of chronic consumption of alcohol on hepatic nonparenchymal systems.

Alterations in hepatic δ-aminolevulinic acid synthetase and heme oxygenase activities after chronic ethanol consumption in rats

In the present study, the effect of chronic ethanol consumption in rats on the hepatic heme metabolism was investigated. Male Wistar rats were fed a nutritionally adequate liquid diet containing ethanol as 36% of the total calories for 5 weeks. After an overnight fast, the livers were excised and centrifuged to obtain mitochondrial and microsomal fractions. Chronic ethanol feeding of rats resulted in about 19% hepatomegaly as represented by the increased liver/body weight ratio. There was no difference in the mitochondrial protein content between the ethanol-treated and control rats, but the microsomal protein content was significantly increased in the ethanol-treated rats. Hepatic microsomal content of cytochrome P-450 (P-450) was markedly enhanced by chronic ethanol ingestion. Microsomal contents of cytochrome b5 (b5) and total heme were also increased to a lesser extent. After chronic ethanol abuse, the hepatic activity of delta-aminolevulinic acid (ALA) synthetase, which is a rate-limiting enzyme for heme production, was significantly increased and that of the heme oxygenase was slightly increased. These data indicate that ALA synthetase activity is induced by the negative feedback mechanism in order to compensate the depletion of heme caused by the utilization of heme for P-450. It is also speculated that, in response to excessive production of heme as described above, heme oxygenase activity is secondarily induced to regulate the amount of heme.

Serum type III procollagen peptide in diagnosis of lung fibrosis due to silicosis and bleomycin toxicity

Early diagnosis of lung fibrosis has been hampered by the lack of a simple, convenient and specific test. Measurement of serum type III procollagen peptide (Pro (III)-N-P) by the method originally developed by Rohde et al. has been shown to be useful for the evaluation of hepatic fibrosis. The present study, therefore, was carried out to investigate the usefulness of the measurement of Pro (III)-N-P in 24 patients with lung fibrosis due to silicosis, and in 7 patients with malignant lymphoma treated with bleomycin, antitumor antibiotic which was the adverse effect of producing fibrosis in the lung. The normal value of the peptide in adults was 8.60 +/- 2.35 ng/ml (mean +/- SD; n = 68) and the normal upper level was set at 13.4 ng/ml (mean +/- 2SD). Patients with silicosis had significantly but not extremely high levels of the peptide and 25% of the patients showed abnormally high values. The level of Pro (III)-N-P was associated with neither physical findings, chest X-p findings nor pulmonary function test results. Three of 7 patients showed increased levels during treatment with bleomycin. In one case, a total dose of 120 mg of bleomycin for over a period of 14 months markedly increased the level of the peptide. These observations suggest that the determination of Pro (III)-N-P may be useful for the detection of lung fibrosis.