Blood pressure adjustment, left ventricular weight and carotid body size in young spontaneously hypertensive rats growing up in hypoxia.

Spontaneously hypertensive rats (SHR) of the Okamoto-Aoki strain grew up in low pressure chambers at a simulated altitude of 4000 m from their 5th to their 18th week of age. Both the sea-level control rats and the hypoxic rats were divided into groups with and without additional hypertonic salt solution. Due to chronic hypoxia the development of systemic hypertension and the left ventricular hypertrophy were diminished in young SHR. In contrast to adult SHR, these effects were attenuated but not abolished by addition of salt. Independently of the salt availability, exposure to long-lasting hypoxia increases the carotid body volume significantly. The data indicate that chronic hypoxia has a stronger effect on carotid body enlargement than different levels of the systemic arterial blood pressure.