Systolic Ventricular Dysfunction Causes Selective Diaphragm Atrophy in Rats

In order to examine the relative impairment of the diaphragm and other skeletal muscles in systolic ventricular dysfunction (VD), their structure and function were compared between rats with VD induced by left coronary artery ligation (n = 17) and sham-operated rats (Co, n = 10). In addition, in an attempt to unravel the mechanism of the observed impairment, we examined alterations in insulin-like growth factor-I (IGF-I) serum levels and IGF-I expression in the liver, diaphragm, and gastrocnemius. In a second series of rats (VD, n = 5 and Co, n = 5) hemodynamic measurements were performed. All measurements were performed 3 mo after the operation. Infarct size averaged 32 ± 10 and 44 ± 20% in the two series, respectively (NS). Hemodynamic measurements revealed a decrease in left ventricular peak systolic pressure of 19% (p < 0.05). Significant diaphragm atrophy (weight: 622 ± 52 mg in VD versus 750 ± 54 mg in Co, p < 0.0005), without alterations in diaphragm contractile properties was present in VD animals...