cyclic-gmp and Sleep-Apnea--Obstructive

Obstructive sleep apnea (OSA) is a highly prevalent disorder that increases the risk of systemic hypertension and cardiovascular diseases. Heme oxygenase (HO) has been shown to be upregulated in patients with OSA and its overexpression in mice causes hypertension. End products of HO are carbon monoxide (CO) and bilirubin. CO exerts a pleiotropic action on vasoregulation. Despite high prevalence and incident of hypertension in OSA, its pathophysiology is not well-understood, particularly in regard to varying susceptibility of patients to hypertension. We investigated the role of HO in endothelial dysfunction and hypertension in OSA.. We determined flow-mediated vasodilatation (FMD) as a measure of endothelial-dependent vasodilatory capacity, exhaled CO, bilirubin, and guanosine 3',5'-cyclic monophosphate (cGMP) in 63 subjects with OSA (normotensive 27, hypertensive 36) and in 32 subjects without OSA (normotensive 19, hypertensive 13).. Hypertensive OSA demonstrated marked impairment in FMD (8.0 ± 0.5% vasodilatation) compared to 10.5 ± 0.8% in hypertensives non-OSA (P < 0.01) and 13.5 ± 0.5% in normotensive OSA (P < 0.001) and 16.1 ± 1.1% in normotensive non-OSA (P < 0.0001). HO was upregulated and plasma nitric oxide (NO) was significantly increased in hypertensive OSA compared to normotensive OSA and hypertensive non-OSA. Conversely, serum cGMP was markedly decreased in hypertensive OSA (12.9 ± 1.8 pmol/ml vs. 20.6 ± 3.7 in normotensive OSA, P = 0.032). There was an inverse relationship between FMD and CO and bilirubin concentrations (r = 0.43, P = 0.0001 and r = 0.28, P = 0.01, respectively).. These data show that increased CO in the setting of elevated NO concentrations is associated with decreased cGMP, impaired FMD, and hypertension in patient with OSA.

Topics: Bilirubin; Carbon Monoxide; Cyclic GMP; Enzyme Activation; Female; Heme Oxygenase (Decyclizing); Humans; Hypertension; Male; Middle Aged; Sleep Apnea, Obstructive; Vasodilation

To investigate the influence of nasal continual positive airway pressure (nCPAP) on the plasma levels of thromboxane B(2) (TXB(2)), renin, angiotensin II (AT-II), endothelin 1 (ET-1), cyclic AMP (cAMP) and cyclic GMP (cGMP) and evaluate their clinical significance.. 20 patients with OSAS without cardiovascular complications and 20 nromal controls were enrolled in the study, who were monitored with PSG, and then treated with nCPAP during the second night. All the plasma parameters were measured after PSG monitoring and nCPAP management with radio-immunoassay.. Before nCPAP, plasma levels of TXB(2), renin, and AT-II were higher in patients with OSAS than those in control (P < 0.05); Meanwhile, the plasma levels of ET-1, cAMP, and cAMP/cGMP were significantly higher in patients group than those in control (P < 0.01).. Patients with severe OSAS may have disturbances in neuro-regulation and changes in plasma level of TXB(2), renin, AT-II and ET-1, which indicates that the vasoactive substance might be related to the hypoxemia and disturbance in neuro-regulations, and might play an important role in the development of hypertension and other cardiovascular disorders. nCPAP therapy can correct the abnormalities of some vasoactive substances.

Topics: Angiotensin II; Cyclic AMP; Cyclic GMP; Endothelin-1; Positive-Pressure Respiration; Renin; Sleep Apnea, Obstructive; Thromboxane B2