Background: Diabetic (DM) inactivation of small conductance calcium-activated potassium (SK) channels contributes to coronary endothelial dysfunction. However, the mechanisms responsible for this down-regulation of endothelial SK channels are poorly understood. Thus, we hypothesized that the altered metabolic signaling in diabetes regulates endothelial SK channels and human coronary microvascular function. Methods: Human atrial tissue, coronary arterioles and coronary artery endothelial cells (HCAECs) obtained from DM and non-diabetic (ND) patients (n = 12/group) undergoing cardiac surgery were used to analyze metabolic alterations, endothelial SK channel function, coronary microvascular reactivity and SK gene/protein expression/localization. Results: The relaxation response of DM coronary arterioles to the selective SK channel activator SKA-31 and calcium ionophore A23187 was significantly decreased compared to that of ND arterioles (p < 0.05). Diabetes increases the level of NADH and the NADH/NAD+ ratio in human myocardium and HCAECs (p < 0.05). Increase in intracellular NADH (100 μM) in the HCAECs caused a significant decrease in endothelial SK channel currents (p < 0.05), whereas, intracellular application of NAD+ (500 μM) increased the endothelial SK channel currents (p < 0.05). Mitochondrial reactive oxygen species (mROS) of HCAECs and NADPH oxidase (NOX) and PKC protein expression in the human myocardium and coronary microvasculature were increased respectively (p < 0.05). Conclusions: Diabetes is associated with metabolic changes in the human myocardium, coronary microvasculature and HCAECs. Endothelial SK channel function is regulated by the metabolite pyridine nucleotides, NADH and NAD+, suggesting that metabolic regulation of endothelial SK channels may contribute to coronary endothelial dysfunction in the DM patients with diabetes.
Bibliographical noteFunding Information:
This research project was supported by the NIH 1R01HL127072-01A1 , 1R01 HL136347-01 , NIGMS / NIH grant (pilot project) 1P20GM103652 and AHA -Grant-in-Aid- 15GRNT25710105 to J.F.; R01-HL-46716 and U54GM115677 to F.W.S, and RO1HL128831, to F.W.S & A.U.
This research project was mainly supported by the National Institutes of Health (NIH) 1R01HL127072-01A1 , 1R01 HL136347-01 , National Institute of General Medical Science (NIGMS) of the NIH [ 5P20-GM103652 (Pilot Project and CORE)] and AHA -Grant-in-Aid (# 15GRNT25710105 ) to J.F. This work was supported in part by R01-HL46716 to F.W.S., RO1HL128831 to F.W.S and A.U.
- Coronary microcirculation
- Endothelial function
- Endothelium-dependent hyperpolarization
- Metabolic syndrome
- SK channels
PubMed: MeSH publication types
- Journal Article