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In experiments on anesthetized dogs it was shown that leukotriene biosynthesis block with quercetin essentially decreased cardiac and hemodynamic disturbances following the immune heart damage (intracoronary injection of anticardiac serum). Blood pressure was reduced by half, with cardiac output and myocardial contractility also decreasing. Pretreatment with quercetin improved coronary stenosis, removing the second phase (15-60 min) of capacity vessel dilatation reaction (blood deposition).

The paper deals with the structure and nomenclature, distribution, metabolism and biological role of leukotrienes, a group of derivatives of eicosanic acids, in the human and animal organism. Leukotrienes can cause contraction of smooth muscles, stimulate the function of leukocytes, and affect the permeability of vessels and arterial pressure. The participation of these substances in the inflammatory processes and allergic reactions is discussed.

Chronic non-specific pulmonary diseases are frequently followed by the development of inflammatory-degenerative and erosive-ulcerative processes in the mucous membrane of the stomach and duodenum. The literature date are presented on the frequency of combination of these conditions, the attempt is made to assess their link from the viewpoint of pathogenesis. Disturbances of respiratory lung function and hypoxia as well as non-respiratory metabolic functions of the pulmonary tissue are regarded as etiological factors of pathological processes in the gastro-duodenal area.

Effects of synthetic leukotriene LTC4 on the internally perfused voltage-clamped snail neurons as well as on the electrical and mechanical activities of the stomach smooth muscle cells were studied. It was found that LTC4 increased calcium inward current in the soma membrane of a cell by activation of both voltage and receptor operated Ca-channels. LTC4 was effective only from outside but not from inside of the membrane which indicated that there was a receptor for leukotrienes in the neuronal membrane.

The effect of LTC4, a synthetic leukotriene, and of BW 755C, a blocker of its biosynthesis on the functioning of Ca-channels in the membrane of snail neurons and on the contractile activity of rat uterus muscles in late terms of pregnancy was studied by means of intracellular dialysis and spontaneous contractility recording techniques. It was found that the 10(-7) mol/l of LTC4 stimulated the contractile function of the rat uterus and activated effectively the Ca-conductance in the somatic membrane of the nervous cell. The action of BW 755C was similar to that of leukotriene on Ca-conductance; in addition BW 755C produced transient activation of contractions of the rat uterus followed by a complete suppression of smooth muscle contractions. Possible mechanisms of the effects described were discussed.