Abstract 13684: Changes in Microvascular Reactivity after Cardiopulmonary Bypass in Patients with Uncontrolled versus Controlled Diabetes
Background: We investigated the effects of cardiopulmonary bypass (CPB) on peripheral arteriolar responses to endothelium-dependent and -independent vasodilators in controlled, uncontrolled, and non-diabetic patients.
Methods: Skeletal muscle arterioles (90-180 µm in diameter) were harvested pre- and post-CPB from non-diabetic (ND) patients (n = 10, HbA1C = 5.2 ± 0.1), controlled diabetic (CDM) patients (n = 10, HbA1C = 6.3 ± 0.15) and uncontrolled diabetic (UDM) patients (n = 10, HbA1C = 9.0 ± 0.3, P<0.05 vs. ND) undergoing coronary artery bypass grafting. In vitro relaxation responses of pre-contracted arterioles were examined in the presence of the endothelium-dependent vasodilators adenosine 5’-diphosphate (ADP) and substance P and the endothelium-independent vasodilator sodium nitroprusside (SNP). The gene expression of endothelium markers and oxidative stress proteins in the skeletal muscle were analyzed by microarray analysis and western blotting.
Results: The pre-CPB vasodilatory responses of uncontrolled, but not controlled diabetic arterioles, to ADP (10-5M), substance P (10-8M), and SNP (10-5M), were significantly diminished compared with those of non-diabetics (P<0.05). The post-CPB arteriolar responses to ADP, substance P and SNP were significantly impaired in all three groups compared to pre-CPB responses (P<0.05). However, these impairments were more pronounced in the uncontrolled diabetic group (P<0.05 vs. non-diabetics). There were no significant changes in the gene expression of endothelial markers between controlled diabetics and non-diabetics. In contrast the expression of oxidative stress proteins in the skeletal muscle was significantly increased in the uncontrolled diabetics (P<0.05 vs. non-diabetics)
Conclusion: Uncontrolled, but not well controlled diabetes is associated with arteriolar endothelium-dependent and -independent vascular dysfunction. In the setting of CPB, poorly controlled diabetes leads to worsened recovery of peripheral arteriolar function, possibly due to the increased oxidative stress. In contrast, the well controlled diabetes is associated with improved peripheral arteriolar function after CPB and cardiac surgery.
- © 2011 by American Heart Association, Inc.