| Abstract: | Pulmonary arterial pressures in native cattle ranging in age from 3 months to 10 yr were found to be increased with increasing altitudes of residence from sea level to 3048 m. At altitudes of 2590 and 3048 m, but not at sea level or 1524 m, the pressures were higher in older than in younger cattle. The magnitude of the pulmonary arterial pressure, and probably the rate of progression of pulmonary hypertension at high altitude, were much less in native cattle than in cattle that were newcomers from low altitude. Natural and artificial selection are believed to have minimized the level of pulmonary hypertension in native high altitude cattle, thus protecting them from high mountain or brisket disease. |
