PMID: 36318Jun 1, 1979

Effect of leucine on the pyridine nucleotide contents of islets and on the insulin released--interactions in vitro with methylene blue, thiol oxidants, and p-chloromercuribenzoate

H P AmmonH Niklas


In the presence of glucose (2 mg/ml), leucine (10 mM) noticeably increased islets' NADPH contents as well as the NADPH:NADP ratio; the changes occurred as soon as 1 min after its addition. NADH concentrations were also increased by leucine. The NADPH:NADP ratio as well as insulin release stimulated by glucose plus leucine were markedly decreased by methylene blue. The thiol oxidants diamide and tert-butyl hydroperoxide also inhibited insulin secretion in response to glucose plus leucine. Employing the perfused pancreas technique, the insulin-releasing action of p-chloromercuribenzoate was further enhanced by leucine. The combined effects were inhibited by tert-butyl hydroperoxide, however. Our data suggest that the insulin-releasing action of leucine depends on the islets' NADPH and reduced glutathione (GSH); in addition, leucine may contribute to insulin secretion by increasing the islet NADPH:NADP ratio and the NADH:NAD ratio. From the data, we assume that the observed increase of NADPH may lead via GSH to an increase in the number of such thiol groups in the beta-cell membrane, which are believed to be related to stimulation of insulin release and, thus, to increase the sensitivity of the beta-cell to stimulation by glucose ...Continue Reading


Sep 1, 1984·Naunyn-Schmiedeberg's Archives of Pharmacology·H P AmmonT Pfäffle
Nov 1, 1981·Naunyn-Schmiedeberg's Archives of Pharmacology·H P Ammon, M Abdel-hamid
Jun 24, 2000·Proceedings of the Society for Experimental Biology and Medicine·L M KarabatasJ C Basabe
Jul 1, 1985·Cell Biochemistry and Function·H P Ammon, M Mark

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