Analysis of L-Arginine supplementation effects on mitochondrial content and function in cultured cells with mitochondrial deficiency

The supplementation with L-Arginine (L-ARG) has been reported as treatment for patients with a mitochondrial disease caused by m.3243A>G mutation. Our aim was to verify the effects of L-ARG on mitochondrial content and function in cells with miochondrial deficiency. We used cybrid cells containing the m.3243A>G mutation and 143B cells (controls). Cells were treated with L-ARG (1mM; 10mM), L-NMMA (Nitric Oxide, NO, Synthase antagonist) and L-ARG+L-NMMA. We evaluated mitochondrial enzyme actvities (citrate synthase, complex II and complex IV, C-IV) and mitocondrial content (SDH-Fp expression). Our results showed that L-ARG had only affected C-IV activities in 143B cells, with an increase with 1mM L-ARG. Treament with 10mM L-ARG had an opposite effect in C-IV activity when compared to 1mM L-Arg. Enzyme activities were not affected by the treatment in m.3243A>G cells. L-Arg had no significant effect on SDH-Fp expression in both cell types. Our results suggest that treatment with 1mM L-ARG decreased NO induced inhibition of C-IV. We thus hypothesize that L-ARG had led to a reduction in NO synthesis or availability. Additional studies are still necessary to clarify the mechanisms of this process.