Journal of Applied Physiology, Vol 52, Issue 6 1571-1574, Copyright © 1982 by American Physiological Society
Evidence for diminished sensitivity of the hamster pulmonary vasculature to hypoxia
B. R. Walker, N. F. Voelkel, I. F. McMurtry and E. M. Adams
Many mammals exhibit elevated pulmonary arterial pressure when exposed to
airway hypoxia. In addition, prolonged hypoxic exposure may result in
elevated hematocrit and right ventricular hypertrophy. The current study
was designed to test whether the hamster, a fossorial species, may possess
naturally selected physiological characteristics advantageous to a
chronically hypoxic environment. Hamsters and rats were studied at low
altitude (1,520 m) and after 5 wk at high altitude (4,250 m). Hematocrit
for low-altitude hamsters was 53 +/- 1 compared with 45 +/- 1 for
low-altitude rats. Low-altitude hamsters and rats demonstrated the same
right ventricular weight-to-total ventricular weight ratio (RV/T) (0.223
+/- 0.006 vs. 0.222 +/- 0.003). After high-altitude exposure the hematocrit
for hamsters and rats was the same (58 +/- 1 vs. 57 +/- 1), but RV/T was
less in the hamster (0.251 +/- 0.004 vs. 0.288 +/- 0.005). In addition, the
hypoxic pulmonary pressor response of lungs isolated from low- and
high-altitude animals was examined. Lungs from hamsters were less
responsive than lungs from rats at all levels of hypoxia tested. In
addition, exposure to altitude resulted in a diminished pressor response in
lungs from both species. It is concluded that the pulmonary vasculature of
the hamster is less responsive to hypoxia than that of the rat, and that
this relative unresponsiveness may aid the hamster in an hypoxic
environment.
