Objectives This experiment is to observe the chronic obstructive sleep apnea syndrome (OSAS) in dogs with the influence of cardiac structural remodelling and function,to discuss dog β-adrenergic receptor (β-AR) expression level change in the ventricular muscle of OSAS, for further study on the ventricular muscle influence OSAS provides theoretical basis.
Methods 1) 14 dogs were randomly divided into normal group (n = 7) and OSAS group (n = 7). Under aseptic conditions, OSAS group do tracheal intubation after anaesthesia daily, and clamping tracheal intubation for 12 weeks to build chronic OSAS model. At the beginning of the two week, clamping the tracheal intubation 1 min every 9min, making apnea/ hypopnea index (AHI) is 6. Subsequently, decreasing interval time 1min every 1 week and maintaining AHI is 20 at last. Normal group is not gived airway obstruction intervention everyday. 2) The heart structure of dogs are measured by echocardiography. 3) Pathohistological and ultrastructural changes were tested by light microscope and transmission electron microscope. 4) The mRNA expression levels of β1-AR, β2-AR and β3-AR of the normal group and OSAS group were detected by RT-PCR experiments.
Results 1) The heart ultrasound shows: the heart construction of OSAS group dog have been increased significantly compared with control group, LVEF has been reduced (p < 0.05).2) Under light microscopy shows: compare with normal group, OSAS group's muscle fibre dissolution, cardiac muscle fibres arranged sparsely; Under the electron microscope, the OSAS group is found swelling in the cell nucleus, and chromatin towards agglutinated; but normal group is no changing.3) Compared with normal group, OSAS group mRNA expression levels of β1-AR decreased in the RT-PCR experiments (p < 0.05) , β2-AR mRNA expression levels slightly decreased (p > 0.05) , and β3-AR mRNA expression levels increased (p < 0.05) .
Conclusions Ventricular structure is remodeled and function are also remodeled in the chronic obstructive sleep apnea. The mRNA of β1 -AR expression levels decreased, the mRNA of β2-AR expression levels decreased, and the mRNA of β3-AR expression levels increased. This change may be relationship between OSAS associated cardiac structure and function changes, or with obstructive sleep apnea syndrome itself influence on β-AR expression level.
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