Upregulation of PPAR[beta]/[delta] Is Associated with Structural and Functional Changes in the Type I Diabetes Rat Diaphragm

Diabetes mellitus is associated with alterations in peripheral striated muscles and cardiomyopathy. We examined diaphragmatic function and fiber composition and identified the role of peroxisome proliferator-activated receptors (PPAR [alpha] and [beta]/[delta]) as a factor involved in diaphragm muscle plasticity in response to type I diabetes. Streptozotocin-treated rats were studied after 8 weeks and compared with their controls. Diaphragmatic strips were stimulated in vitro and mechanical and energetic variables were measured, cross bridge kinetics assessed, and the effects of fatigue and hypoxia evaluated. Morphometry, myosin heavy chain isoforms, PPAR [alpha] and [beta]/[delta] gene and protein expression were also assessed. Diabetes induced a decrease in maximum velocity of shortening (-14%, P