AJP - Heart and Circulatory Physiology, Vol 259, Issue 6 1667-H1673, Copyright © 1990 by American Physiological Society
Coronary and myocardial adaptations to high altitude in dogs
K. W. Scheel, E. Seavey, J. F. Gaugl and S. E. Williams
Department of Physiology, Texas College of Osteopathic Medicine, Fort Worth 76107-2690.
The objective of this study was to determine whether exposure to high
altitude (hypoxic hypoxemia) induces coronary and/or collateral growth.
Fourteen mongrel dogs were maintained at a simulated altitude of 18,000 ft
for 1 mo and 7 dogs maintained for 3 mo. Within 2 days after their sojourn,
the following data were obtained at ambient pressure: pulmonary, right
heart chamber, and wedge pressures as well as cardiac output. On an
isolated heart preparation, coronary and collateral flows were determined;
each vessel was injected with a different color tracer; and the heart was
sliced, separated by perfusion territories, and examined for myocardial
hypertrophy. We found that pulmonary artery pressures in altitude-adapted
animals were higher compared with controls, and coronary flow per gram was
increased after 1 mo of exposure but not different from control after 3 mo.
Collateral flows were not significantly different from that of control
animals, and biventricular hypertrophy occurred with right ventricular
dominance. Comparing these results with those that we obtained previously
from anemic animals, we favor the hypothesis that oxygen availability
rather than blood flow velocity is most likely linked to vascular growth.
