Calcium flux and cystic fibrosis [letter].

In an effort to determine whether increased permeability to calcium ions could 
explain the cystic fibrosis-serum ciliary dyskensia factor response in the tracheal 
test system, we selectively increased the membrane permeability of the tracheal 
epithelium to calcium ions by adding calcium ionophore A23187 to the 
tracheal culture medium. These studies determined that calcium ionophore A23187 in 
culture medium produced a change in mucociliary function in the tracheal 
test system indistinguishable from that promoted by C.F. sera. These investigations, 
which are now being extended to include the ultrastructural alterations induced 
in the epithelium of the rabbit tracheal bioassay system, point to 
an important role for calcium as a cofactor in the production 
of the C.D.F. response generated by the C.F sera. The C.F. 
serum substance seems to act at the cellular-membrane level, promoting membrane-permeability 
changes (at least with respect to calcium) in the rabbit tracheal 
test system. Such a mechanism would not necessarily result in a 
net physiological imbalance of calcium in the rabbit tracheal system but 
only local changes in calcium concentration that would subsequently alter secretion 
and microtubular function. Since C.F. serum, like sweat and saliva from 
these same patients, can promote ionic fluxes, perhaps there is a 
common factor in all these body-fluids which is related to the 
basic defect in C.F. It is tempting to speculate that such 
a factor produces a membrane-associated phenomenon that may be generally representative 
of the in-vivo C.F. disorder and as such may reflect the 
nature of the cellular and glandular abnormalities of the disease. 