Cardiovascular and respiratory responses to chronic intermittent hypoxia in adult female rats

Abstract

New Findings: What is the central question of this study? Chronic intermittent hypoxia (CIH) induces hypertension in male rats. There is evidence that the development of high blood pressure in females is attenuated in other models of hypertension. Due to the lack of information about the cardiovascular effect of CIH in female rats, we set out to determine whether female rats develop hypertension after CIH. What is the main finding and its importance? Different from other experimental models of hypertension, adult female rats develop high blood pressure after CIH. These findings provide new perspectives for a better understanding of the neural mechanisms underlying the development of hypertension in females. Adult male rats develop hypertension in response to chronic intermittent hypoxia (CIH). Female rats are known to be protected against the development of hypertension in several experimental models. In this study, we aimed to verify whether the development of hypertension was also prevented in female rats exposed to CIH. Adult female rats were submitted to 35 days of CIH, 8 h per day. At the end of the CIH protocol, the rats were anaesthetized for the implantation of an arterial catheter and the next day the mean arterial pressure and heart rate were recorded in conscious rats. Considering that changes in the respiratory pattern have been associated with the development of hypertension in the CIH model, the respiratory pattern of adult female rats was also evaluated after CIH exposure using whole-body plethysmography. Adult female rats submitted to CIH (n = 27) presented a significant increase in mean arterial pressure when compared with the control group (n = 26). Moreover, CIH-exposed female rats presented an increase in the frequency and duration of apnoeas when compared with control rats. These data show that adult female rats develop changes in the respiratory pattern and high blood pressure in response to CIH.