M. Mcguire et A. Bradford, Chronic intermittent hypoxia increases haematocrit and causes right ventricular hypertrophy in the rat, RESP PHYSL, 117(1), 1999, pp. 53-58
Chronic continuous hypoxia increases haematocrit and causes right ventricul
ar hypertrophy and pulmonary hypertension. In obstructive sleep apnoea, the
exposure to hypoxia is intermittent rather than continuous but the effects
of chronic intermittent hypoxia on haematocrit and right ventricular mass
are unclear. Wistar rats were exposed to alternating periods of hypoxia and
normoxia twice per min for 8 h per day for 5 weeks in order to mimic the i
ntermittent hypoxia of obstructive sleep apnoea in humans. Haematocrit was
significantly raised at day 7, 14, 21, 28 and 35 of the treatment period. A
t the end of the treatment, there was a significant increase in right ventr
icular mass. Therefore, chronic intermittent hypoxia increases haematocrit
and right heart mass. These results suggest that the raised haematocrit and
pulmonary arterial pressure observed in some cases of obstructive sleep ap
noea in humans may be caused by intermittent nocturnal hypoxaemia. (C) 1999
Elsevier Science B.V. All rights reserved.