RESUMO
AIMS: The objective was to re-examine endothelial function, insulin mediated vasodilation and glucose extraction in the forearm of patients with type 2 diabetes (T2DM) and matched control subjects (CON) to investigate whether blood flow impairments result from diabetes per se or from concurrent disease. METHODS: 18 subjects (10 with T2DM, 8 CON) had graded brachial artery infusions of endothelial dependent (acetylcholine: 15, 30, 60 microg/min), endothelial independent (sodium nitroprusside: 1, 3, 10 microg/min) and partially endothelial mediated (adenosine: 50, 150, 500 microg/min) vasodilators. The protocol was repeated during a hyperinsulinemic clamp. Forearm blood flow and glucose extraction were measured at each dose of vasodilator (with/without insulin). Measurements were also taken in the control arm, reflecting systemic insulin infusion only. RESULTS: Non-insulin mediated increases in bulk forearm blood flow were similar in T2DM and CON. However, insulin mediated forearm blood flow responses and glucose extraction were lower in T2DM versus CON. CONCLUSION: The vasodilatory effect of insulin is impaired in T2DM although bulk flow capacity is maintained. Insulin mediated glucose extraction is reduced during concomitant maximal stimulation of forearm blood flow with endothelial-dependent vasodilators, despite maintaining flow. This is consistent with previous work that associates T2DM with impaired insulin mediated capillary recruitment.
Assuntos
Glicemia/metabolismo , Diabetes Mellitus Tipo 2/fisiopatologia , Insulina/farmacologia , Vasodilatação/fisiologia , Acetilcolina/administração & dosagem , Acetilcolina/farmacologia , Adenosina/administração & dosagem , Adenosina/farmacologia , Velocidade do Fluxo Sanguíneo/efeitos dos fármacos , Velocidade do Fluxo Sanguíneo/fisiologia , Glicemia/efeitos dos fármacos , Pressão Sanguínea , Artéria Braquial/efeitos dos fármacos , Artéria Braquial/fisiologia , Artéria Braquial/fisiopatologia , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/tratamento farmacológico , Endotélio Vascular/fisiopatologia , Meia-Vida , Humanos , Hipoglicemiantes/uso terapêutico , Infusões Intra-Arteriais , Pessoa de Meia-Idade , Nitroprussiato/administração & dosagem , Nitroprussiato/farmacologia , Consumo de Oxigênio , Valores de Referência , Vasodilatação/efeitos dos fármacos , Vasodilatadores/administração & dosagem , Vasodilatadores/farmacologiaRESUMO
UNLABELLED: Patients with T2DM have an increased risk of CVD. Prevention of CVD represents the major goal of all treatment of T2DM, and early intervention in those patients at particularly high risk is important.We measured the insulin sensitivity and plasma biomarkers of CVD to determine whether a home-based exercise training program improves biomarker levels and insulin sensitivity. Patients with T2DM (n=12), IGT (n=4) and healthy control subjects (n=9) were studied before and after eight weeks of exercise training by rowing ergometry at 65-70% of peak oxygen uptake. CONCLUSIONS: 1) patients with T2DM have elevated plasma concentrations of CVD biomarkers compared to the matched control and IGT groups; 2) a moderate to vigorous intensity home-based training program did not reduce plasma concentrations of these CVD markers; 3) insulin sensitivity improved as a result of exercise training in the control group, but not in the T2DM group.
