Calcium and sodium transport processes in patients with cystic fibrosis 2. Mg2+- dependent, Ca2+ ATPase activity in fibroblast membrane preparations from cystic fibrosis patients and controls.

Mg2+-dependent Ca2+-ATPase activity was determined in membrane preparations of fibroblasts grown from skin biopsies of cystic fibrosis patients and age-matched controls. This enzyme was stimulated by increasing free calcium concentrations with an apparent Kdiss for calcium of approximately 45 micron. Although there was a great deal of variation in Ca2+-ATPase activity observed between individual strains, there was a significant decrease in the maximal activation of the Ca2+-ATPase in membrane preparations of fibroblasts obtained from cystic fibrosis patients compared to the controls (P less than 0.05). This observation indicates that decreased Ca2+-ATPase activity is a generalized phenomenon in cystic fibrosis found in more than one cell-type. This decrease in Ca2+-ATPase activity may have a number of implications that may explain some of the manifestations of the disease.