Influence of D-Glucose upon the Respiratory and Secretory Response of Insulin- producing Tumor Ceils to 2-Aminobicyclo[2,2,lJheptane-2-carboxylic Acid1

In insulin-producing cells of the RINmSF line, the nonmetabolized analogue of i.-leucine, 2-aminobicyclo|2,2,1 |heptane-2-carboxylic acid de creases <), consumption, lowers ATP content, and inhibits insulin release despite stimulation of both Ml, production and "(<)., output from cells prelabeled with L-|i/-uC]glutamine. The metabolic and secretory effects of 2-aminobicyclo|2,2,l|heptane-2-carboxylic acid are opposed to those of D-glucose, which increases respiration, ATP content, and insulin release, while lowering Ml, production and "< (), output from the prelabeled cells. D-Glucose also antagonizes the inhibitory action of 2aminobicyclo|2,2,l|heptane-2-carboxylic acid upon both respiration and secretion. These findings suggest that, in tumor as in normal islet cells, the regulation of insulin release by exogenous nutrients depends on the availability of endogenous ATP.