Catabolism of Histamine in vivo
The material covered in this chapter is limited to experiments in living mammals, excluding man, in which some evidence of catabolism of histamine has been presented. Studies in man are considered in Chapter 4, Section F; in vitro catabolism in Chapter 4,
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Catabolism of Histamine in vivo By
RICHARD W. SCHAYER With 1 figure
I. Introduction The material covered in this chapter is limited to experiments in living mammals, excluding man, in which some evidence of catabolism of histamine has been presented. Studies in man are considered in Chapter 4, Section F; in vitro catabolism in Chapter 4, Section C; and absorption and excretion in Chapter 4, Section A.
n. Early studies The earliest studies on histamine catabolism were limited to in vitro and perfusion experiments (Chapter 4, Section C). In this section the in vivo work preceding the introduction of isotopes is considered. In these early experiments it was usually essential to use large quantities of histamine; hence, the results are not necessarily valid for physiological situations. DRAGSTEDT and MEAD (1935) found that after intravenous injection of 0.5 and 1.0 mg/kg doses of histamine into anesthetized dogs, histamine could still be detected in blood after 2 minutes but not after 5 minutes. BINET and MARQUIS (1935) showed that lung of living dogs either removed or inactivated histamine. ROSE and BROWNE (1938) found rapid disappearance of intravenously injected histamine in rats and its appearance in a number of tissues; particularly high concentrations were found in kidney. Adrenalectomy markedly retarded the disappearance of injected histamine from the tissues. The latter change is not apparent when very small doses of histamine are used (SCHAYER et aI., 1952). ALEXANDER (1944) observed that mice efficiently destroyed small amounts of injected histamine; after large doses, metabolism was retarded and large quantities could be recovered unchanged in the urine. EMMELIN (1951) gave cats histamine intravenously in various concentrations over a period of several hours. The rapid decrease in arterial histamine concentration which was observed persisted even in eviscerated or nephrectomized cats. There was evidence of retention of histamine in kidney following large doses. COHEN (1954) tied off loops of jejunen of anesthetized fasted rats and tested the fate of histainine under various conditions. In all cases there was little destruction since about 90 % of the histamine could be recovered. Perfusion of rat small intestine in 8itu showed evidence of its ability to destroy histamine (VALETTE and COHEN, 1956). M. Rocha e Silva (ed.), Histamine and Anti-Histaminics © Springer-Verlag Berlin Heidelberg 1966
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Imidazoleaeetic acid riboside
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Histamine
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Unknown products fanned hy condensation or other nonoxidative reactions
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1,4-Methylimidazole
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