Metabolic and secretory responses of parotid cells to cationic amino acids. Oxidation of the amino acids and interference with the oxidation of d-glucose or endogenous nutrients

Abstract

Cationic amino acids were recently found to stimulase amylase release from rat parotid cells. The possible relevance of their oxidative catabolism to such a secretory stimulation was investigated d-Glucose, which was efficiently metabolized in parotid cells and which augmented O 2 uptake above basal value, failed to affect basal or stimulated amylase release. l-Arginine, l-lysine and l-histidine failed to stimulate the oxidation of either exogenous d-[6- 14C]glucose or endogenous nutrients in cells pre-labelled with [U- 14C]palmitate or l-[U- 14C]glutamine. The oxidation of l-[U- 14C]arginine, l-[U- 14C]ornithine, l-U 14C]lysine and l-[U- 14C]histidine, all tested at a 10mM concentration, was much lower than that of d-[U- 14]glucose (5.6mM). These findings argue against the view that the stimulation of amylase release by cationioc amino acids would be related to their role as a source of energy in the parotid cells.