oligomycins and Cystic-Fibrosis

A disorder of calcium (Ca2+) metabolism may be central to the pathogenesis of cystic fibrosis (CF). Average cellular Ca2+ levels in fibroblasts derived from patients with CF (ages, 14-25 yr; n = 25) were 36-77% higher than in matched controls depending on age of cell culture (9.0-10.6 versus 5.1-7.8 nmol/mg cellular protein). Cellular Ca2+ was significantly elevated in CF, but was not a reliable criterion for identifying CF cells because of the high variability of results. Studies of Ca2+ fluxes in cell organelles showed that mitochondria isolated from CF fibroblasts accumulate 2-3 times more Ca2+ than controls [79.5 +/- 8.2 versus 33.7 +/- 4.7 nmols X mg mitochondrial protein-1 X 10 min-1 (+/- SD)], Ca2+ accumulation in mitochondrial reliably distinguished between CF and control or heterozygote cells (P less than 0.0005, n = 11). In vitro experiments showed that Ca2+ influx and efflux are increased in isolated CF mitochondria, resulting in net Ca2+ accumulation. Ca2+ uptake in mitochondria is energy-dependent; some inhibitors of mitochondrial energy metabolism (atractyloside, oligomycin) influenced Ca2+ intake significantly more in CF than in control mitochondria. Furthermore, the average activities of NADH oxidase, NADH- and succinate-cytochrome c reductase were 77, 58, and 48% higher in CF mitochondria, respectively. This indicates that many functions associated with energy metabolism and the mitochondrial membrane (electron transport, ATP transport, and ATP hydrolysis) are not operating properly in CF, thus possibly causing the derangement of Ca2+ metabolism found in CF mitochondria and cells.

Topics: Adenosine Triphosphate; Adolescent; Adult; Antimycin A; Atractyloside; Calcium; Cystic Fibrosis; Electron Transport; Female; Fibroblasts; Heterozygote; Humans; Intracellular Membranes; Male; Microsomes; Mitochondria; Oligomycins; Rotenone; Ruthenium Red

Calcium uptake by mitochondria isolated from skin fibroblasts of patients with cystic fibrosis and controls was studied in the presence and absence of inhibitors. Since mitochondrial calcium accumulation may be supported by ATP hydrolysis or respiration, inhibitors of each were used to characterize the basis of previously described alterations in calcium uptake by mitochondria from patients with cystic fibrosis. Calcium uptake measurements under the influence of oligomycin and antimycin A suggest that the increased calcium uptake by mitochondria from patients with cystic fibrosis is related to altered respiratory system activity. Binding constants of calcium to the carrier system in mitochondria were not different between genotypes.

Topics: Adenosine Triphosphate; Antimycin A; Calcium; Cystic Fibrosis; Fibroblasts; Humans; Hydrolysis; Mitochondria; Oligomycins; Oxygen Consumption; Skin