Calmodulin in normal and cystic fibrosis human intestine at different developmental stages.

Calmodulin concentrations and localisation have been analysed as a function of development in human intestinal epithelial cells from normal and cystic fibrosis individuals. In normal fetuses up to eight weeks of gestation intestinal epithelial cells which were still undifferentiated were not immunoreactive and their calmodulin content was low. From eight weeks onwards there was a significant overall increase in calmodulin content concomitant with its segregation to the apical side of epithelial cells. At 14 weeks of gestation calmodulin concentrations and localisation closely resembled those of adults. The developmental pattern of calmodulin appeared to parallel the morphological and functional maturation of brush borders which occurs during the first trimester of pregnancy. In the intestinal epithelial cells from a 19 weeks cystic fibrosis fetus and a cystic fibrosis newborn infant neither calmodulin concentration, nor its localisation were affected. Similarly, brush border calmodulin binding proteins and enzymatic activities were similar in normal subjects and the cystic fibrosis intestine.