Influence of altitude on heart and breathing rates in some Peruvian rodents

¹ Instituto de Biologia Andina, Universidad Nacional Mayor de San Marcos, Lima, Peru; and Departments of Zoology and Physiology, University of Wisconsin, Madison, Wisconsin

Heart and breathing rates were measured at 0.1 and 4.5 km before, during, and after Nembutal anesthesia in Phyllotis darwini chilensis, P. d. rupestris, P. osilae, P. pictus, Akodon amoenus, A. berlepschii, A. jelskii, and A. boliviensis; in Mus musculus rates were measured at 3.9–4.5 km, and in P. d. limatus, M. musculus, and the white mouse at 0.1 km. None of the high-altitude mice and only the native Phyllotis (+25%) of the low-altitude mice showed a circulatory response to altitude. All the low-altitude mice but only Akodon (+22%) of the high-altitude mice showed a respiratory response to altitude. The native mountain species had higher resting heart and breathing rates than did the lowland forms.