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Histaminase activity in rat lung
248
Pharmacological Research. Vol. 22. Supplement 2.1990
HISTAMINASE ACTIVITY IN RAT LUNG Ignesti G., Banchelli M.G., Raimondi L., Pirisino R. and Buffoni F.. Department of Preclinical and Clinical Pharmacology, University of Florence. Histamine is generally considered a good substrate of tissue diamine oxidase enzymes (DAO; amine:oxygen oxidoreductase (deaminating)(copper containing); E.C.l.4.3.6.). Absence of DAO activity in rabbit, rat (Rao et al.,1986), human (Hesterberg et al ., 1984) and pig lung (Bieganski and Vlatowska, 1983) was observed. These negative results were obtained with the method of Okuyama and Kobayashi (1961) in which··14-C putrescine was used as substrate. This paper describes the results obtained from rat lung in the study of the oxidative deamination of putrescine and histamine. With the Okuyama and Kobayashi method any oxidative deamination of putrescine in any subcellular fractions of rat lung (mitochondria, microsomes, 10000 g and 105000 g supernatants) at pH 6.5 and 7.4 was undetectable, whereas an appreciable activity was observed at pH 8 .5. At this pH value the oxidation of putrescine is strongly inhibited by o; -aminaguanidine and by histamine and spermine. The oxidation of histamine was studied by the method o~ .Snyder and Hendley (1968). A very high histaminase activity was found in rat lung microsomes at pH 7.4 and at pH 8.5 . This activity is inhibited by x-aminoguanidine and it is resistant to deprenyl,a MAO inhibitor. The observation of a high histaminase activity in rat lung at physiological pH appears quite important to explain the metabolic degradation of histamine in this tissue. Buffoni F.: Pharmacol. Rev., 18, 1163-1199, 1966. Rao B.,Prasad Rao K.S., Mehendale H.M.: Biochem. J.,234, 733-36,1986. Hesterberg R., Sattler J., Lorenz W., Stahlknecht C.D., Barth H., Crombach M., Weber D.: Agents Actions~ 14, 326-334, 1984. Okuyama T., Kobayashi J.: Arch. Biochem. Biophys. , 95, 242-250,1961. Bieganski T., Vlatowska M.A.: Agents Actions, 13, 257-262, 1983. Snyder S.H.,Hendley E.D.: J. Pharmacol. Exp. Ther., 163, 386-392, 1968.
1043-6618/90/22110248-01/$03.00/0
© 1990 The Italian Pharmacological Society
Pharmacological Research. Vol. 22. Supplement 2.1990
HISTAMINASE ACTIVITY IN RAT LUNG Ignesti G., Banchelli M.G., Raimondi L., Pirisino R. and Buffoni F.. Department of Preclinical and Clinical Pharmacology, University of Florence. Histamine is generally considered a good substrate of tissue diamine oxidase enzymes (DAO; amine:oxygen oxidoreductase (deaminating)(copper containing); E.C.l.4.3.6.). Absence of DAO activity in rabbit, rat (Rao et al.,1986), human (Hesterberg et al ., 1984) and pig lung (Bieganski and Vlatowska, 1983) was observed. These negative results were obtained with the method of Okuyama and Kobayashi (1961) in which··14-C putrescine was used as substrate. This paper describes the results obtained from rat lung in the study of the oxidative deamination of putrescine and histamine. With the Okuyama and Kobayashi method any oxidative deamination of putrescine in any subcellular fractions of rat lung (mitochondria, microsomes, 10000 g and 105000 g supernatants) at pH 6.5 and 7.4 was undetectable, whereas an appreciable activity was observed at pH 8 .5. At this pH value the oxidation of putrescine is strongly inhibited by o; -aminaguanidine and by histamine and spermine. The oxidation of histamine was studied by the method o~ .Snyder and Hendley (1968). A very high histaminase activity was found in rat lung microsomes at pH 7.4 and at pH 8.5 . This activity is inhibited by x-aminoguanidine and it is resistant to deprenyl,a MAO inhibitor. The observation of a high histaminase activity in rat lung at physiological pH appears quite important to explain the metabolic degradation of histamine in this tissue. Buffoni F.: Pharmacol. Rev., 18, 1163-1199, 1966. Rao B.,Prasad Rao K.S., Mehendale H.M.: Biochem. J.,234, 733-36,1986. Hesterberg R., Sattler J., Lorenz W., Stahlknecht C.D., Barth H., Crombach M., Weber D.: Agents Actions~ 14, 326-334, 1984. Okuyama T., Kobayashi J.: Arch. Biochem. Biophys. , 95, 242-250,1961. Bieganski T., Vlatowska M.A.: Agents Actions, 13, 257-262, 1983. Snyder S.H.,Hendley E.D.: J. Pharmacol. Exp. Ther., 163, 386-392, 1968.
1043-6618/90/22110248-01/$03.00/0
© 1990 The Italian Pharmacological Society