The role of histamine1 and histamine2 receptors in the ethanol-induced jejunal plasma protein loss
Histamine and other mediators have been shown to be involved in the ethanol-induced jejunal plasma protein loss. In this study we have investigated whether the histamine (H)-related component of this protein loss is mediated by H1-receptors, H2-receptors or both. Four groups of dogs (n=12 in each) were studied. They were: untreated, H1+H2-receptor blockade, H1-receptor blockade and H2-receptor blockade. Chlorpheniramine and ranitidine were used to block H1 and H2-receptor blockade. Chlorpheniramine and ranitidine were used to block H1 and H2-receptors respectively. In all animals, jejunal protein loss was measured over 10 min periods for 90 min. Ethanol increased protein loss in all time periods (p<0.001). This protein loss was depressed by H1+H2-receptors blockade throughout 90 min (p<0.01). H1-receptor blockade caused a similar depression of ethanol effect but only during 20 to 40 min (p<0.05). In contrast, H2-receptor blockade aggravated the protein losing effect of ethanol throughout 90 min (p<0.01). Analyses of data tend to suggest that the ethanol-induced protein loss is mediated principally by H1-receptors, and that a complete inhibition of the histamine-related ethanol-induced protein loss can be achieved only by a simultaneous blockade of both H1 and H2- receptors, and not by H1- or H2-receptor blockade alone.
KeywordsHistamine Plasma Protein Ranitidine Complete Inhibition Histamine2 Receptor
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