INTRINSIC FLUORESCENCE CHANGES IN NERVE TERMINALS, EVOKED BY ACTION POTENTIALS, ARE MODULATED BY KREBS CYCLE SUBSTRATES

Abstract

Electrical stimulation of the mammalian neurohypophysial infundibular stalk evokes the entry of Na+and Ca2+into the neurosecretory terminals during the action potential. These events, in turn, increase intracellular Ca2+and activate NaK - and Ca -ATPases, prompting the mitochondria to increase oxidative phosphorylation which can be monitored by recording the changes in FAD and NADH fluorescence. This paper reflects our efforts to determine whether or not modulating the capacity of mitochondria to produce ATP, by changing the concentrations of two important substrates of the Krebs cycle of the nerve terminal mitochondria, pyruvate and glucose, has an effect on the intrinsic fluorescence changes triggered by action potential stimulation.