作者:H Detert、A Hagelüken、R Seifert、W Schunack
DOI:10.1016/0223-5234(96)88235-3
日期:1995.1
The cationic-amphiphilic 2-substituted histamines, 2-(3-chlorophenyl)histamine (2-[2-(3-chlorophenyl)-1H-imidazol-4-yl]ethanamine) and 2-(2-cyclohexylethyl)histamine, activate pertussis toxin-sensitive guanine nucleotide-binding proteins (G-proteins) of the G(i)-subfamily by a receptor-independent mechanism. We studied structure-activity relationships of 2-substituted histamine derivatives for this G-protein activation using six known and 12 newly synthesized compounds. Elongation of the alkyl chain between imidazole and the ring system enhanced the potency and efficiency of substances in activating high-affinity GTP hydrolysis, ie the enzymatic activity of G-protein alpha-subunits, in membranes of HL-60 leukemic cells. Cyclopentyl-, cyclohexyl- and norbornyl-substituted histamines were more effective and potent than phenyl-substituted histamines in mediating G-protein activation in HL-60 membranes and in activating reconstituted bovine brain G(i)/G(o)-proteins. Our data show that the chain length and the type of ring system are important determinants for receptor-independent G-protein activation by 2-substituted histamines. With respect to histamine H-1-receptors, most of the substances studied displayed weak antagonistic activity.