The Toxicologist - Society of Toxicology

espiratory tract anatomy, lung physiology, and clearance mechanisms. Limited
data have found significant differences in the airway morphometry of two mouse
strains with different genetic backgrounds. Therefore, the objectives of this study
are to: 1) generate tracheobronchial (TB) morphometry data for the C57Bl/6
mouse; and 2) compare obtained TB data with those reported for the Balb/c and
B6C3F1 mouse strains. To accomplish this, silicone rubber replica lung casts were
prepared in the intact thorax of both male and female C57Bl/6 mice. Each TB airway
was assigned an unique binary number and the airway length, diameter and
branching angle was measured. No differences were observed between male and female
mice of similar body weight and age. However differences in airway length
and diameter were observed among all three inbred mouse strains. These differences
have implications to the health outcomes during an inhalation study and in
the extrapolation from animal toxicological data to humans.
596 DECREMENTS IN HEART RATE VARIABILITY IN A
ATHEROSCLEROTIC MOUSE MODEL DUE TO
EXPOSURE TO SEMI-VOLATILE COMPONENTS OF
ULTRAFINE CONCENTRATED AMBIENT
PARTICULATES.
A. J. Keebaugh 1 , G. Gookin 1 , M. MacKinnon 1 , K. Salazar 1 , L. Mendez 2 , D.
Meacher 1 , C. Sioutas 3 and M. Kleinman 1 . 1 Medicine, University of California,
Irvine, Irvine, CA, 2 Microbiology and Molecular Genetics, University of California,
Irvine, Irvine, CA and 3 Civil and Environmental Engineering, University of Southern
California, Los Angeles, CA.
Increased levels of concentrated ambient particulates (CAPs) are associated with adverse
cardiovascular effects including morbidity and mortality. Ultrafine particles
(diameter