Nitric oxide synthase inhibition attenuates the skeletal muscle VEGF mRNA response to exercise

Abstract

Vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and transforming growth factor-beta(1) (TGF-beta(1)) mRNA increase in rat skeletal muscle in response to a single acute exercise bout. Nitric oxide (NO) is released locally by muscle vascular endothelium and muscle fibers during exercise, contributes to the blood flow response to exercise, and regulates mitochondrial respiration. We hypothesized that a reduction in NO production, via NO synthase inhibition, would demonstrate a link between NO and the VEGF, bFGF, and TGF-beta(1) gene responses to exercise. To investigate this hypothesis, 9-wk-old female Wistar rats were divided into eight treatment groups (n = 6 each): 1) saline + rest, 2) saline + exercise, 3) 30 mg/kg N(omega)-nitro-L-arginine methyl ester (L-NAME, a known NOS inhibitor) + rest, 4) 30 mg/kg L-NAME + exercise, 5) 300 mg/kg L-NAME + rest, 6) 300 mg/kg L-NAME + exercise, 7) 300 mg/kg N(omega)-nitro-D-arginine methyl ester (D-NAME, inactive enantiomer of L-NAME) + rest, and 8) 300 mg/kg D-NAME + exercise. Exercise consisted of 1 h of running at 20 m/min on a 10 degrees incline. VEGF, TGF-beta(1), and bFGF mRNA from left gastrocnemius were analyzed by quantitative Northern blot. Submaximal exercise for 1 h increased VEGF mRNA 4.2-fold and TGF-beta(1) mRNA 1.5-fold in untreated rats but did not increase bFGF mRNA. The exercise-induced increase in VEGF mRNA was attenuated approximately 50% by 30 and 300 mg/kg L-NAME; the TGF-beta(1) mRNA increase was unaffected by 300 mg/kg L-NAME. In addition, 300 mg/kg D-NAME had no effect on the exercise-induced increase in VEGF mRNA. Administration of 300 mg/kg L-NAME had no effect on bFGF mRNA. These findings suggest that NO is important in the regulation of the VEGF gene response to exercise through increases in VEGF transcription or by increases in the VEGF mRNA half-life.

L-Arginine Supplementation Causes Additional Effects on Exercise-Induced Angiogenesis and VEGF Expression in the Heart and Hind-Leg Muscles of Middle-Aged Rats

“…Cardiac capillary density and VEGF mRNA expression were markedly lower in eNOS -/-than in wild-type mice [12]. The inhibition of NOS diminished the exercise-induced increase in mRNAs for VEGF [23] and VEGFR-1 [24] and in protein levels of VEGF and VEGFR-2 [25] in rat skeletal muscles. Moreover, NOS inhibition failed to cause capillary angiogenesis induced by chronic electrical stimulation in rat skeletal muscle [11,25].…”

Acute ethanol increases angiogenic growth factor gene expression in rat skeletal muscle

“…This suggests that the mechanisms responsible for the exercise-induced increase in bFGF mRNA may also be responsible for the ethanol-induced increase in bFGF mRNA. It has previously been demonstrated that bFGF gene expression is insensitive to hypoxia, nitric oxide (NO), or circulating angiotensin II in skeletal muscle (8,12,20,21). However, resting skeletal muscle bFGF mRNA is reduced in response to prostacyclin (8).…”

“…In skeletal muscle, endurance training results in increases in oxidative enzymes and in the number of capillaries (3,13,42). Our laboratory has shown that acute exercise can increase angiogenic growth factor (VEGF, TGF-␤ 1 , and bFGF) mRNA in rat skeletal muscle (20,21,24). In the course of these investigations into the regulation of skeletal muscle angiogenic growth factor expression, an unanticipated increase in VEGF expression with the use of ethanol as a solvent for drug administration was found.…”

Age-associated declines in mitochondrial biogenesis and protein quality control factors are minimized by exercise training

“…The intensity of the exercise program was carefully matched in these two groups by V O2 max data, as described previously (43,45). Earlier studies have shown that this intensity of running significantly alters the biochemical profile of gastrocnemius muscle (16,45,53,55). The animals were killed two days after the last exercise training session to avoid the metabolic effects of the final run.…”