Lower capillarization, VEGF protein, and VEGF mRNA response to acute exercise in the vastus lateralis muscle of aged vs. young women

Abstract

In humans, the majority of studies demonstrate an age-associated reduction in the number of capillaries surrounding skeletal muscle fibers; however, recent reports in rats suggest that muscle capillarization is well maintained with advanced age. In sedentary and trained men, aging lowers the number of capillaries surrounding type II, but not type I, skeletal muscle fibers. The fiber type-specific effect of aging on muscle capillarization is unknown in women. Vascular endothelial growth factor (VEGF) is important in the basal maintenance of skeletal muscle capillarization, and lower VEGF expression is associated with increased age in nonskeletal muscle tissue of women. Compared with young women (YW), we hypothesized that aged women (AW) would demonstrate 1) lower muscle capillarization in a fiber type-specific manner and 2) lower VEGF and VEGF receptor expression at rest and in response to acute exercise. Nine sedentary AW (70 + 8 yr) and 11 YW (22 + 3 yr) had vastus lateralis muscle biopsies obtained before and at 4 h after a submaximal exercise bout for the measurement of morphometry and VEGF and VEGF receptor expression. In AW compared with YW, muscle capillary contacts were lower overall (YW: 2.36 + 0.32 capillaries; AW: 2.08 + 0.17 capillaries), specifically in type II (YW: 2.37 + 0.39 capillaries; AW: 1.91 + 0.36 capillaries) but not type I fibers (YW: 2.36 + 0.34 capillaries; AW: 2.26 + 0.24 capillaries). Muscle VEGF protein was 35% lower at rest, and the exercise-induced increase in VEGF mRNA was 50% lower in AW compared with YW. There was no effect of age on VEGF receptor expression. These results provide evidence that, in the vastus lateralis of women, 1) capillarization surrounding type II muscle fibers is lower in AW compared with YW and 2) resting VEGF protein and the VEGF mRNA response to exercise are lower in AW compared with YW.

Timing Is Everything: Age of Onset Influences Long-Term Retinopathy Risk in Type 2 Diabetes, Independent of Traditional Risk Factors

“…Interestingly, levels of vascular endothelial growth factor (VEGF) and IGF-I, both potent angiogenic growth factors implicated in the development of diabetic retinopathy, have been found to vary with age in diabetes (12,13). Additionally, the VEGF expression in response to a stimulus is lessened in older versus younger individuals (14).…”

The Capillary Pattern in Human Masseter Muscle During Ageing

“…Lower muscle capillarization is accompanied with lower VEGF expression (Croley et al, 2005;Ryan et al, 2006). Angiogenic potential seems not to be disturbed in masseter muscle with age.…”

“…Similarly, in human muscles capillary supply has been reported to be either maintained (Denis et al, 1986;Proctor et al, 1995;Lyon et al, 2007) or reduced (Coggan et al, 1992;Frontera et al, 2000;Croley et al, 2005;Ryan et al, 2006).…”

“…Most of the published studies on skeletal muscles counted capillary profiles and presented their results either as the number of capillary profiles per number of muscle fibre profiles (C/F), per muscle cross-sectional area (CD) or around a fibre profile (CAF), or the number of capillary contacts per fibre (CC) (Degens et al, 1994;Hepple and Vogell, 2004;Croley et al, 2005;Mathieu-Costello et al, 2005;Ryan et al, 2006;Čebašek et al, 2010). Further, in human posterior crycoarythenoideus muscle (PCA) Lyon et al (2007) estimated the length of capillaries per fibre and separately for each fibre type volume and surface area, using the orientator method.…”

Computational Model of VEGF Spatial Distribution in Muscle and Pro-Angiogenic Cell Therapy

“…VEGF receptor concentrations and kinetic rates were chosen based on in vivo measurements of total VEGFR2 protein concentration and capillary density in human vastus lateralis skeletal muscle [39,40]. For that tissue, total protein concentration in skeletal muscle is assumed to be 150 mg/g muscle [41], endothelial cell surface area is 1,000 lm 2 , and capillary diameter is 7 lm.…”