Inhibitory action of novel arginine derivative on catecholamine secretion evoked by acetylcholine from cultured bovine adrenal chromaffin cells

A novel product, 4-amino-5-guanidinopentanoic acid 15-[(4-aminobutyl)-3-aminopropylcarbamoyl] pentadecyl ester (Arg-HSA-Spm), was synthesized based on ptilomycalin A, which is one of the extracts from marine sponge. Arg-HSA-Spm contains arginine in its chemical structure. The pharmacological action of Arg-HSA-Spm on catecholamine secretion from cultured bovine adrenal chromaffin was examined. Arg-HSA-Spm inhibited catecholamine secretion stimulated by the physiological secretagog acetylcholine. This inhibitory action of Arg-HSA-Spm on catecholamine secretion induced by 10(-4) M acetylcholine was dose-dependent from 10(-8) M to 10(-5) M. In the presence of 3 x 10(-7) M Arg-HSA-Spm, the stimulation of catecholamine secretion observed by increasing acetylcholine Up to 10(-3) M did not reach the maximal level observed without Arg-HSA-Spm. Arg-HSA-Spm at 10(-5) M suppressed both the increase in intracellular free Ca2+ level and the influx of Ca-45(2+) induced by 10(-4) M acetylcholine. The Arg-HSA-Spm-induced suppression of intracellular free Ca2+ level, the influx of Ca-45(2+) and catecholamine secretion were not observed in the presence of extracellular K+ at 56 mM. The results presented in this study suggested that Arg-HSA-Spm may inhibit the influx of extracellular Ca2+ into the cells, probably through its blocking action related to acetylcholine receptors, resulting in the inhibition of catecholamine secretion in adrenal Chromaffin cells.