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Systemic arterial pressure at maturity in rats following chronic hypoxia in early life
Bryan Ross1, Matthew McIntosh, Demetra Rodaros
1Department of Physiology, McGill University, Montréal, Quebec, Canada.
Insights
Early-life hypoxia in rats significantly increases mature systolic blood pressure and decreases arterial compliance. This suggests postnatal stress can cause lasting vascular changes, potentially increasing cardiovascular risk in susceptible individuals.
Area of Science:
- Cardiovascular Physiology
- Developmental Biology
- Environmental Health
Background:
- Investigated the long-term impact of early-life hypoxemia on adult systemic arterial blood pressure.
- Utilized Sprague-Dawley rats to model the effects of reduced oxygen exposure in early development.
Purpose of the Study:
- To determine if prolonged hypoxia during early development affects blood pressure and vascular function in adulthood.
- To explore potential mechanisms linking early-life stress to mature cardiovascular health.
Main Methods:
- Rats were exposed to hypoxia (FiO₂ = 0.12) for the first 10 days of life, followed by normoxia.
- Adult blood pressure and aortic pulse wave velocity were measured using telemetry and in anesthetized rats, respectively.
- Compared outcomes between hypoxia-pretreated and age-matched control groups.
Main Results:
- Hypoxia-pretreated rats exhibited significantly higher systolic, mean, and pulse pressures in adulthood.
- Elevated aortic pulse wave velocity was observed in hypoxia-pretreated rats, indicating reduced arterial compliance.
- Increased blood pressure variability was noted in males exposed to early-life hypoxia.
Conclusions:
- Prolonged early-life hypoxia leads to sustained hypertension in mature rats, likely due to decreased arterial compliance.
- Postnatal stress can induce long-lasting vascular alterations, increasing the risk of hypertension later in life.
- Findings suggest potential cardiovascular risks for adult survivors of conditions involving early-life hypoxia, such as congenital cyanotic heart disease.
Background:
The effect of prolonged hypoxemia in early life on systemic arterial blood pressure at maturity was assessed in Sprague-Dawley rats.
Methods:
Animals hypoxic in early life (12 males, 10 females) were raised in hypoxia (FiO₂ = 0.12) for the first 10 days of life and subsequently raised in normoxia, along with age-matched controls (11 males, 9 females). At 2 months of age, arterial blood pressure was recorded intravascularly using telemetry in awake and unrestrained animals over two 12-h night-time (active) and daytime (resting) periods. Aortic pulse wave velocity was assessed in six additional hypoxic pretreated and five control anesthetized 2-month-old male rats.
Results:
Systolic, mean, and pulse pressures were significantly greater in the hypoxic pretreated group compared to the control group during resting and active periods in both sexes (P ≤ 0.05). Diastolic pressure and heart rate did not differ between the two groups. Hypoxic pretreated males displayed significantly increased blood pressure variability during the resting period. Aortic pulse wave velocity was also found to be elevated in the hypoxic pretreated rats.
Conclusions:
Prolonged hypoxic stress in early life in the rat is associated with increased systolic arterial pressure at maturity very likely due to decreased arterial compliance. These findings suggest that a nutrient-independent, postnatal stress may lead to long-lasting vascular alterations predisposing to increased arterial pressure at maturity. This raises the possibility that adult survivors of congenital cyanotic cardiac disease may be at risk for secondary cardiovascular morbidity unrelated to surgical repair or residual cardiac defects.
