Journal of Applied Physiology, Vol 51, Issue 6 1607-1611, Copyright © 1981 by American Physiological Society
Alterations in responses to drugs of atria from white rats acclimated to hypobaric hypoxia
M. J. Hughes, M. T. Kopetzky, F. Messiha, K. Light and C. D. Barnes
To test the hypothesis that acclimation to simulated high altitude (SHA)
may occur in the tissues as well as in the systemic regulatory apparatus of
an organism, atria isolated from young rats acclimated to SHA of 6,000 m
and from control rats were observed under normoxic conditions. SHA atria
have slower spontaneous heart rates than atria isolated from controls (209
+/- 4 vs. 228 +/- 3, P less than 0.001). SHA atria are more sensitive to
pentobarbital sodium (P less than 0.001) and ethanol (P less than 0.06):
spontaneous mechanical activity stops at a lower drug concentration in SHA
than in control atria. SHA atria are less sensitive to norepinephrine in
the concentration range of 7.9 X 10(-9) to 3.1 X 10(-6) M and respond to
increased bath concentrations (3.8, 5.8 and 7.8 mM) of calcium with a
significantly (P less than 0.04) smaller chronotropic response and a
greater inotropic response than atria from control animals. These data
support the above-mentioned hypothesis.
