Cardiovascular Responses Induced by Obstructive Apnea Are Enhanced in Hypertensive Rats Due to Enhanced Chemoreceptor Responsivity

Abstract

Spontaneously hypertensive rats (SHR), like patients with sleep apnea, have hypertension, increased sympathetic activity, and increased chemoreceptor drive. We investigated the role of carotid chemoreceptors in cardiovascular responses induced by obstructive apnea in awake SHR. A tracheal balloon and vascular cannulas were implanted, and a week later, apneas of 15 s each were induced. The effects of apnea were more pronounced in SHR than in control rats (Wistar Kyoto; WKY). Blood pressure increased by 57±3 mmHg during apnea in SHR and by 28±3 mmHg in WKY (p<0.05, n = 14/13). The respiratory effort increased by 53±6 mmHg in SHR and by 34±5 mmHg in WKY. The heart rate fell by 209±19 bpm in SHR and by 155±16 bpm in WKY. The carotid chemoreceptors were then inactivated by the ligation of the carotid body artery, and apneas were induced two days later. The inactivation of chemoreceptors reduced the responses to apnea and abolished the difference between SHR and controls. The apnea-induced hypertension was 11±4 mmHg in SHR and 8±4 mmHg in WKY. The respiratory effort was 15±2 mmHg in SHR and 15±2 mmHg in WKY. The heart rate fell 63±18 bpm in SHR and 52±14 bpm in WKY. Similarly, when the chemoreceptors were unloaded by the administration of 100% oxygen, the responses to apnea were reduced. In conclusion, arterial chemoreceptors contribute to the responses induced by apnea in both strains, but they are more important in SHR and account for the exaggerated responses of this strain to apnea.

Association between Glaucoma and Obstructive Sleep Apnea Syndrome: A Meta-Analysis and Systematic Review

“…In recent years, OSAS has been increasingly recognized as a risk factor for both systemic and ocular diseases. For example, past studies have demonstrated that the risks of developing diabetes, stroke, hypertension, and atherosclerosis are increased in OSAS patients [ 5 , 43 , 44 ]. In ophthalmology, besides glaucoma, papill edema, non-arteritic ischemic optic neuropathy (NAION), and other ocular disorders have also been considered as potential lesions due to intermittent nocturnal hypoxia caused by OSAS [ 4 , 45 , 46 ].…”

Airway obstruction produces widespread sympathoexcitation: role of hypoxia, carotid chemoreceptors, and NTS neurotransmission

“…) or the pressor response (Angheben et al. ) to airway obstruction. Collectively, these findings indicate that activation of carotid chemoreceptor afferents partially contribute to the sympathetic and cardiorespiratory changes during airway obstruction.…”

“…A 15 sec balloon inflation decreases arterial O 2 saturation~20%, increases CO 2 and respiratory effort, and produces a pressor response (Schoorlemmer et al 2011). Carotid body denervation (CBD) attenuates the cardiovascular responses to airway obstruction in nonanesthetized rats (Angheben et al 2014). Furthermore, CBD did not reduce the neuronal activation evoked by obstructive apnea in ventrolateral medulla of regions involved in the respiratory and autonomic control (Ferreira et al 2015).…”

“…However, the increase in PNA and sympathoexcitation induced by airway obstruction was partially attenuated. These results are consistent with previous report that CBD did not reduce Fos immunoreactivity in ventrolateral medulla of autonomic and respiratory regions (Ferreira et al 2015) or the pressor response (Angheben et al 2014) to airway obstruction. Collectively, these findings indicate that activation of carotid chemoreceptor afferents partially contribute to the sympathetic and cardiorespiratory changes during airway obstruction.…”

“…Carotid body denervation (CBD) attenuates the cardiovascular responses to airway obstruction in nonanesthetized rats (Angheben et al. ). Furthermore, CBD did not reduce the neuronal activation evoked by obstructive apnea in ventrolateral medulla of regions involved in the respiratory and autonomic control (Ferreira et al.…”