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

Population doubling time, kinetics of transport of alpha-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.