Mineral Content of Calcified Tissues in Cystic Fibrosis Mice ** LARA R. GAWENIS, 1 P AULETTE SPENCER, 4 LAURA S. HILLMAN, 3 MATTHEW C. HARLINE, 1 J. STEVEN MORRIS, 2 AND LANE L. CLARKE* ,1 1 Dalton Cardiovascular Research Center and the Department of Veterinary Biomedical Sciences, 2 Missouri University Research Reactor Center, 3 Department of Child Health, University of Missouri–Columbia, Columbia, MO 65211, and 4 the Department of Oral Biology, University of Missouri–Kansas City School of Dentistry, Kansas City, MO 64108 Received December 26, 2000; Accepted February 16, 2001 ABSTRACT Although abnormal hard tissue mineralization is a recognized complication of cystic fibrosis (CF), the pathogenesis leading from the defective cystic fibrosis transmembrane conductance regulator (CFTR) protein is poorly understood. We hypothesized that CFTR plays a direct role in the mineralization of bone and teeth and tested the hypothesis using CF mouse models [CFTR(–) mice]. In vivo measure- ments by dual-emission X-ray absorpitometry (DEXA) indicated that bone mineral density (BMD) was reduced in CF mice as compared to gender-matched littermates. However, no change was evident after correction of BMD for the covariant of body weight. The latter finding was confirmed in isolated femurs and nasal bones by standard dry- ashing and instrumental neutron activation analysis (INAA). INAA of the continuously growing hypsodont incisor teeth from CFTR(–) mice revealed reduced Ca and normal P in the enamel layer—a finding con- sistent with changes in the deciduous teeth of CF children. Interest- ingly, enamel fluoride was increased in the CFTR(–) incisors and may associate with abnormal enamel crystallite formation. The iron content of the incisor enamel was reduced, explaining the loss of yellow pig- mentation in CFTR(–) incisors. In contrast to the incisors, the mineral © Copyright 2001 by Humana Press Inc. All rights of any nature, whatsoever, reserved. 0163-4984/01/8301/0069 $13.25 * Author to whom all correspondence and reprint requests should be addressed. ** Preliminary reports published in Pediatric Pulmonology, 14, 253A (1997) and 15, 253A (1998). Biological Trace Element Research 69 Vol. 83, 2001