Different alterations in the insulin-stimulated glucose uptake in the athlete's heart and skeletal muscle.

Abstract

Physical training increases skeletal muscle insulin sensitivity. Since training also causes functional and structural changes in the myocardium, we compared glucose uptake rates in the heart and skeletal muscles of trained and untrained individuals. Seven male endurance athletes (VO2max 72±2 ml/kg/min) and seven sedentary subjects matched for characteristics other than VO2max (43±2 ml/kg/min) were studied. Whole body glucose uptake was determined with a 2-h euglycemic hyperinsulinemic clamp, and regional glucose uptake in femoral and arm muscles, and myocardium using "F-fluoro-2-deoxy-D-glucose and positron emission tomography. Glucose uptake in the athletes was increased by 68% in whole body (P < 0.0001), by 99% in the femoral muscles (P < 0.01), and by 62% in arm muscles (P = 0.06), but it was decreased by 33% in the heart muscle (P < 0.05) as compared with the sedentary subjects. The total glucose uptake rate in the heart was similar in the athletes and control subjects. Left ventricular mass in the athletes was 79% greater (P < 0.001) and the meridional wall stress smaller (P < 0.001 ) as estimated by echocardiography. VO2max correlated directly with left ventricular mass (r = 0.87, P < 0.001) and inversely with left ventricular wall stress (r = -0.86, P < 0.001). Myocardial glucose uptake correlated directly with the rate-pressure product (r = 0.75, P < 0.02) and inversely with left ventricular mass (r = -0.60, P < 0.05) or with the whole body glucose disposal (r = -0.68, P < 0.01). Thus, in athletes, (a) insulin-stimulated glucose uptake is enhanced in the whole body and skeletal muscles, (b) whereas myocardial glucose uptake per muscle mass is reduced possibly due to decreased wall stress and energy requirements or the use of alternative fuels, or both. (J. Clin. Invest. 1994Invest. . 2267Invest. -2274

Insulin resistance characterizes glucose uptake in skeletal muscle but not in the heart in NIDDM

“…Patients with IDDM [23,24] with no CHD have insulin resistance in skeletal muscle but no alteration in cardiac work or myocardial glucose uptake under insulin-stimulated conditions. In contrast, in athletes with a decrease in cardiac work per heart mass, insulin-stimulated glucose uptake in the heart is diminished, while peripheral insulin sensitivity is enhanced [14]. In patients with essential hypertension, the opposite picture emerges: heart glucose uptake and cardiac work per unit heart mass are increased in proportion to the elevation of blood pressure, while peripheral insulin sensitivity is decreased [25].…”

“…Similarly, concentrations of plasma NEFA are inversely correlated with rates of FDG uptake [12] and arterial-coronary sinus glucose differences [22]. Several indices of cardiac work are also directly correlated with glucose uptake under normoglycaemic hyperinsulinaemic conditions [12,14,23] where glucose is the main fuel for heart energy production.…”

“…M-mode and two-dimensional echocardiography (Aloca SSD-870; Aloca Co. Ltd., Tokyo, Japan) were performed, and Penn-cube left ventricular mass was calculated as previously described [14,15].…”

Consumo de frutose e exercício físico, impacto na síndrome metabólica.

“…Evidenciou-se menor concentração circulante de insulina e maior sensibilidade ao hormônio em atletas, quando comparados a indivíduos sedentários (EBELING et al, 1993;NUUTILA et al, 1994). Atletas másteres apresentam maior proteção contra o comprometimento da tolerância à glicose associada ao envelhecimento (ROGERS et al, 1989).…”

Understanding Obesity and the Influence of Acculturation on Metabolic Responses in East Asian Populations in the United States

“…Physical activity is a bodily movement resulting in energy expenditure while exercise is defined as a type of physical activity which is planned, structured, and repetitive, and performed to improve or maintain one or more components of physical fitness (ACSM, 2006). Sedentary activity, such as television viewing, is associated with an increased relative risk of developing T2DM for both men and women (Hu, 2003;Hu, Leitzmann et al, 2001 (Ebeling et al, 1993;Nuutila et al, 1994;Richter, Turcotte, Hespel, & Kiens, 1992). Japanese patients with T2DM and Chinese individuals with impaired glucose tolerant benefited from exercise interventions to increase muscle insulin mediated glucose uptake and reduce the rate of developing T2DM, respectively (X. R. Pan et al, 1997;Tamura et al, 2005).…”