The mechanism of the increase in resistance against lethal doses of histamine developed by previous injections of small histamine doses

Kovách, Arisztid and Beznák, Aladár and Gáspár-Rády, Zsuzsanna (1947) The mechanism of the increase in resistance against lethal doses of histamine developed by previous injections of small histamine doses. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 17. pp. 278-293. ISSN 0365-3005

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Abstract

1. ) Comparative determination of the O₂ contents of guinea pigs' blood proved, that the cause of the resistance to a s. c. injected LD of H in the resistant HT animals is better oxygenation. 2. ) This better oxygenation is due to a decreased contraction response of the broncho- and vaso-constrictor muscles to the same level of H in the blood, since determination of the blood in normal, nonresistant HT guinea pigs showed no significant difference. 3. ) The small and irregular relative diminution of the blood H after s. c. H injections, in the HT animals accords well with the small and irregular slowing down of adsorption of H from the site of injection (peritoneal cavity) and with the circumstance that i. c. injected H disappears from the blood equally fast in both normal and HT animals. 4. ) The blood lactic acid content of the HT animals is higher than that of the normal ones. During H shock the CO₂ content of the blood is highest in the normal, and lowest in the resistant HT animals. The diminished contraction of the smooth muscles in the lungs cannot therefore be conditioned solely by the acidaemia. 5. ) The possible physiological mechanism of the decreased responsiveness caused by HT is discussed. It is pointed out that alt present the likeliest explanation is that HT damages the broncho- and the vaso-constrictor muscles which consequently are unable to contract and allow a better oxygenation, and increased blood flow through the lungs, This hypothesis is supported by the autopsy results.

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