Role of calcium and calmodulin in the regulation of the rabbit ileal brush-border membrane Na super(+)/H super(+) antiporter

The role of Ca super(2+)/calmodulin (CaM)-dependent phosphorylation in regulation of the brush-border Na super(+)/H super(+) antiporter, which is believed to be part of the neutral linked NaCl absorptive process, was studied using purified brush-border membrane vesicles, which contain both the Na super(+)/H super(+) antiporter and Ca super(2+)/CaM-dependent protein kinase(s) and its phosphoprotein substrates. The authors conclude that Ca super(2+), acting through CaM, regulates ileal brush-border Na super(+)/H super(+) exchange, and that this may be involved in the regulation of neutral linked NaCl absorption.