HIGHLIGHTED TOPIC Physiology and Pathophysiology of Sleep Apnea Acute and chronic cardiovascular effects of intermittent hypoxia in C57BL/6J mice

Campen, M. J., L. A. Shimoda, and, C. P. O’Donnell. Acute and chronic cardiovascular effects of intermittent hypoxia in C57BL/6J mice. J Appl Physiol 99: 2028–2035, 2005. First published July 7, 2005; doi:10.1152/japplphysiol.00411.2005.—We investigated the effects of 1) acute hypoxia and 2) 5 wk of chronic intermittent hypoxia (IH) on the systemic and pulmonary circulations of C57BL/6J mice. Mice were chronically instrumented with either femoral artery or right ventricular catheters. In response to acute hypoxia (4 min of 10% O2; n 6), systemic arterial blood pressure fell (P 0.005) from 107.7 2.5 to 84.7 6.5 mmHg, whereas right ventricular pressure increased (P 0.005) from 11.7 0.8 to 14.9 1.3 mmHg. Another cohort of mice was then exposed to IH for 5 wk (O2 nadir 5%, 60-s cycles, 12 h/day) and then implanted with catheters. In response to 5 wk of chronic IH, mice (n 8) increased systemic blood pressure by 7.5 mmHg, left ventricle septum weight by 32.2 7.5 10 2 g/100 g body wt (P 0.015), and right ventricle weight by 19.3 3.2 10 2 g/100 g body wt (P 0.001), resulting in a 14% increase in the right ventricle/left ventricle septum weight (P 0.005). We conclude that in C57BL/6J mice 1) acute hypoxia causes opposite effects on the pulmonary and systemic circulations, leading to preferential loading of the right heart; and 2) chronic IH in mice results in mild to moderate systemic and pulmonary hypertension, with resultant leftand right-sided ventricular hypertrophy.