| Abstract: | In the experiments on isolated frog sartorius muscles, amines and amides were found to inhibit the process of stimulation of D-xylose transport induced by insulin, 2,4-dinitrophenol or potassium contracture. The inhibitory action was produced by urea, acetamide, guanidine, NH4Cl, mono-, di- and trimethyl- or ethylamines, some diamines (all the substances being, applied in the concentration range equal to 100 mM). The similar effect was obtained when cystamine (20 mM), tryptamine, 5-methoxytryptamine (2 mM) and adenine, adenosine, guanosine (1-10 mM) were used. There was no inhibitory effect of acetone, glycerol, tetraethylammonium, propilamine, butylamine, aminoacids, spermine, spermidine, ATP, AMP or cAMP. It has been suggested that the inhibitory substances may interact by producing hydrogen bonds from NH-groups with the neutrally or negatively charged groups at the external surface of the muscle membrane in the region with a slow hydrophobicity. As a result, no structural changes required for activation of the sugar transport system occur in the membrane. |
