Impaired fasting blood glucose is associated with increased endothelin-1 vasoconstrictor tone

The experimental aim of this study was to determine whether ET-1-mediated vasoconstrictor tone is elevated in adult humans with impaired fasting blood glucose concentrations, independent of other cardiovascular risk factors.

Forearm blood flow (FBF: plethysmography) responses to intra-arterial infusion of selective ETA receptor blockade (BQ-123: 100 nmol/min for 60 min) and non-selective ETA/B blockade (BQ-123 + BQ-788: 50 nmol/min for 60 min) were determined in 28 middle-aged, sedentary adults (17 M/11 F): 14 with normal fasting blood glucose (age: 57 ± 2 yr; 6 F/8 M; BMI: 29.2 ± 0.9 kg/m(2); glucose: 4.9 ± 0.1 mmol/L) and 14 impaired fasting blood glucose (58 ± 1 yr; 5 F/9 M; 29.6 ± 1.1 kg/m(2); 5.8 ± 0.1 mmol/L) concentrations.

Selective ETA receptor blockade elicited a significantly greater (∼20%) increase in FBF in the impaired fasting glucose adults compared with the normoglycemia controls. ETA/B blockade resulted in a further 2-fold increase (P < 0.05) in FBF above that elicited by ETA receptor antagonism in the impaired fasting glucose but not normal fasting glucose adults. There was a positive correlation between fasting blood glucose levels and the peak vascular responses to ETA (r = 0.44; P < 0.05) and ETA/B (r = 0.62; P < 0.05) blockade. No other anthropometric, hemodynamic or metabolic variable was correlated with the blood flow responses to ET-1 receptor blockade.

ET-1-mediated vasoconstrictor tone is elevated in adults with impaired fasting blood glucose concentrations, independent of other cardiometabolic risk factors. Enhanced ET-1 system activity may underlie endothelial vasomotor dysfunction and increased cardiovascular risk in adults with impaired fasting blood glucose concentrations.