Abnormal Skeletal Muscle Capillary Recruitment During Exercise in Patients With Type 2 Diabetes Mellitus and Microvascular Complications

• Published in: Journal of the American College of Cardiology Vol. 53; no. 23; pp. 2175 - 2183
• Main Authors: Womack, Lisa, MS, Peters, Dawn, PhD, Barrett, Eugene J., MD, PhD, Kaul, Sanjiv, MD, Price, Wendie, RN, Lindner, Jonathan R., MD
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 09.06.2009; Elsevier; Elsevier Limited
• Subjects: Biological and medical sciences; Brachial Artery - physiology; Brachial Artery - physiopathology; Capillaries - pathology; Capillaries - physiopathology; Cardiology; Cardiology. Vascular system; Cardiovascular; Case-Control Studies; contrast ultrasound; diabetes mellitus; Diabetes Mellitus, Type 2 - diagnostic imaging; Diabetes Mellitus, Type 2 - physiopathology; Diabetes. Impaired glucose tolerance; Diabetic Angiopathies - diagnostic imaging; Diabetic Angiopathies - physiopathology; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Exercise - physiology; Female; Humans; Insulin; Insulin resistance; Internal Medicine; Male; Medical sciences; microbubbles; microvascular dysfunction; Middle Aged; muscle perfusion; Muscle, Skeletal - blood supply; Muscle, Skeletal - diagnostic imaging; Muscle, Skeletal - pathology; Muscular system; Regional Blood Flow; Rodents; Studies; Ultrasonography; CRP; DM + MC; NO; nitric oxide; C-reactive protein; contrast-enhanced ultrasound; capillary blood volume; DM; diabetes mellitus with microvascular complications; diabetes mellitus; pulsing interval; microvascular dysfunction; CEU; microbubbles; VI; video intensity; contrast ultrasound; CBV; PI; muscle perfusion; Endocrinopathy; Type 2 diabetes; Physical exercise; Human; Metabolic diseases; Cardiovascular disease; Striated muscle; Recruitment; Vascular disease; Microangiopathy; Exercise tolerance test; Circulatory system; Cardiology
• ISSN: 0735-1097; 1558-3597
• DOI: 10.1016/j.jacc.2009.02.042

Objectives We sought to determine whether skeletal muscle capillary recruitment is impaired in type 2 diabetes mellitus (DM) with and without microvascular complications (MC). Background Insulin and exercise each stimulate recruitment of skeletal muscle capillaries. Insulin-mediated recruitment is impaired in insulin-resistant humans and animals, but exercise-mediated recruitment has not been studied. Methods We studied 20 control subjects, 22 patients with DM, and 8 patients with DM + MC. With the patients under fasting conditions, contrast-enhanced ultrasound perfusion imaging of the forearm flexor muscles was performed to evaluate capillary blood flow and blood volume at rest and during low- or high-intensity contractile exercise (25% and 80% maximal handgrip). Rheologic parameters of erythrocyte deformability and plasma viscosity were measured. Results Muscle capillary responses to exercise were similar between the control and DM groups, but were reduced (p < 0.05) in those with DM + MC. The DM + MC group had a ≈50% reduction in capillary recruitment and a ≈60% to 70% reduction in capillary blood flow during both low- and high-intensity exercise compared with the control group. These abnormalities were independent of disease duration. Patients with DM + MC were more insulin resistant than DM patients and had an elevated whole blood viscosity that correlated with plasma glucose (p = 0.001) and C-reactive protein (p = 0.003). Conclusions Capillary recruitment during low- and high-intensity exercise is normal in uncomplicated type 2 DM but is impaired in those with microvascular complications. Abnormalities in capillary recruitment may be related to abnormal hemorheology, although larger trials are needed to establish this relation.