Robert J. Feigal

Altered Intracellular Calcium in Fibroblasts from Patients with Cystic Fibrosis and Heterozygotes

Summary: The importance of intracellular calcium (Ca) in secretion and transmembrane ion movement led us to study Ca in cells from patients with cystic fibrosis (CF) which is a lethal genetic exocrinopathy. Skin fibroblasts from patients with CF, obligate heterozygotes (HZ), and age- and sex-matched controls (C) were used in matched pair experiments measuring 45Ca exchange into and efflux from the cells over time. CF cell lines and HZ cell lines exhibit increased 45Ca exchange when compared with their respective controls (P < 0.005). The magnitude of this difference (approximately 30%) is not reduced when cells are washed with lanthanum chloride after the exchange period. This difference is likely attributable to an altered capacity of one or more of the intracellular Ca sequestering organelles. Further evidence for this explanation was seen in 46Ca efflux experiments in which CF cells retained a higher percent of their initial 0-time 45Ca than did C cells late in the efflux period (P < 0.05). The finding of an altered Ca pool size in both CF and particularly HZ cells suggests that altered Ca metabolism is related to the basic gene defect in CF.Speculation: Increased intracellular Ca in CF cells, while necessarily secondary to the basic gene defect, may influence cellular metabolism sufficiently to be a basis for many events in the pathogenesis of the disease. The presence of the Ca pool size alteration in cells from obligate heterozygotes is evidence that this phenomenon is closely related to the basic gene defect.

Doubling time α-aminoisobutyrate transport and calcium exchange in cultured fibroblasts from cystic fibrosis and control subjects

Abstract Population doubling time, kinetics of transport of α-aminoisobutyrate (AIB) and calcium (Ca) exchange were studied in skin fibroblast monolayers obtained from 5 subjects with cystic fibrosis (CF) and 5 age- and sex-matched controls. Population doubling time as estimated from cell count, protein and DNA was no different in the two groups. KM, Vmax, maximal uptake and time of half maximal uptake of AIB were no different in the two groups. Intracellular Ca pool size based on exchange of 45Ca with unlabelled Ca was significantly greater in monolayers from CF subjects.

The calcium abnormality in cystic fibrosis mitochondria: Relative role of respiration and ATP hydrolysis

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.