Fluorometric detection of ADP/ATP carrier deficiency in human muscle

Defects in mitochondrial energy metabolism lead to severe disorders in huma ns referred to as mitochondriocytopathies. Most of them have been reported to result from deficiencies of one or more complexes of the respiratory cha in and, more rarely, from mitochondrial transmembrane metabolite carrier de fects. Dysfunctioning of the ADP/ATP carrier, which catalyses the export of matrix ATP in exchange for cytosolic ADP, has been demonstrated to induce myopathies in mouse and in humans. To screen for ADP/ATP carrier deficiency in patients suffering from mitochondriocytopathy with no defined etiology, we have set up a fluorometric assay to quantify the ADP/ATP carrier in sma ll muscle homogenates, without preliminary isolation of mitochondria. The a ssay is based on the use of a fluorescent derivative of atractyloside., nam ely naphthoyl-atractyloside, a highly specific inhibitor of ADP/ATP transpo rt. Here, we describe analysis of healthy and pathological muscle samples, and characterization of ADP/ATP carrier deficiencies in two patients, one d isplaying an absence of the carrier and the second one containing a limited amount of the carrier with altered binding properties. (C) 2001 Elsevier S cience B,V. All rights reserved.