Ventilation and metabolism among rat strains.
Strohl, Kingman P., Agnes J. Thomas, Pamela St. Jean, Evelyn H.
Schlenker, Richard J Koletsky, Nicholas J. Schork.
Departments of Medicine, Human Genetics, and Epidemiology and
Biostatistics, Case Western Reserve University, Cleveland OH, 44106;
and Department of Physiology and Pharmacology, the University of
South Dakota, Vermillion, SD, 57069
APStracts 3:0451A, 1996.
We examined ventilation and metabolism in four rat strains with
variation in traits for body weight and/or blood pressure regulation.
Sprague-Dawley (SD = 8M,8F), Brown Norway (BN = 10M,11F), and Zucker
(Z = 11M,12F) rats were compared with Koletsky (K = 11M,11F) rats.
Using non-invasive plethysmography, frequency, tidal volume, minute
ventilation, oxygen consumption, and carbon dioxide production were
derived at rest during normoxia (room air), and during the fifth
minute of exposure to each of the following: hyperoxia (100% oxygen),
hypoxia (10% oxygen/balance nitrogen), and hypercapnia (7% carbon
dioxide/balance oxygen). Statistical methods probed for strain and
sex effects, with co-variant analysis by body weight, length, and
body mass. During resting breathing, strain effects were found with
respect to both frequency (BN,Z>K,SD), and tidal volume
(SD>BN,Z), but not to minute ventilation. Sex influenced
frequency (F>M) alone. Zucker rats had higher values for
oxygen consumption, carbon dioxide production, and respiratory
quotient than the other three strains with no independent effect by
sex. During hyperoxia, frequency was greater in Brown Norway and
Zucker than in Sprague Dawley or Koletsky; Sprague Dawley, had a
larger tidal volume than Brown Norway or Zucker; Zucker, a greater
minute ventilation than Koletsky; and males, a larger tidal volume
than females. Strain differences persisted during hypercapnia, with
Zucker rats exhibiting the highest frequency and ventilation values.
During hypoxic exposure, strain effects were found to influence
minute ventilation (SD>K,Z), frequency (BN>K) and tidal
volume (SD>BN,K,Z). Body mass was only a modest predictor of
minute ventilation during normoxia, of both minute ventilation and
tidal volume with hypoxia, hypercapnia, or hyperoxia, and of
frequency during hypercapnia. We conclude that among rats, strain,
more than the effect of body mass or sex, has major and different
influences on metabolism, the pattern and level of ventilation during
air breathing, and ventilation during acute exposure to hypercapnia
or hypoxia.
Received 23 April 1996; accepted in final form 13 September 1996.
APS Manuscript Number A391-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996