Nitric oxide, VEGF, and VEGFR-2: interactions in activity-induced angiogenesis in rat skeletal muscle

Abstract

Vascular endothelial growth factor (VEGF) is considered to be important in promotion of capillary growth in skeletal muscles exposed to increased activity. We studied its interactions with nitric oxide (NO) by examining the expression of endothelial NO synthase (NOS), VEGF, and VEGF receptor-2 (VEGFR-2) proteins in relation to capillary growth in rat extensor digitorum longus muscles electrically stimulated for 2, 4, or 7 days with and without NOS inhibition by N(omega)-nitro-L-arginine (L-NNA, 3 mg/day). Stimulation increased all proteins from 2 days onward, concomitantly with capillary proliferation (labeling for proliferating cell nuclear antigen). Capillary-to-fiber ratio was elevated by 25% after 7 days. Concurrent oral administration of L-NNA did not affect the increase in endothelial NOS but depressed its activity, as shown by increased blood pressure and decreased arteriolar diameters in 2-day-stimulated muscles. NOS inhibition eliminated the increased expression of VEGFR-2 and VEGF proteins in muscles stimulated for 2 and 4 days but not for 7 days. However, it depressed capillary proliferation and the increase in C/F at all time points. We conclude that, in stimulated muscles, NO, generated by activation of neuronal NOS by muscle activity or endothelial NOS by increased blood flow and capillary shear stress, may increase capillary proliferation in the early stages of stimulation through upregulation of VEGFR-2 and VEGF. With longer stimulation, capillary growth appears to require NO, and high levels of VEGF and VEGFR-2 may be contributing to maintenance of the increased capillary bed.

Thrombospondin-1 Inhibits Nitric Oxide Signaling via CD36 by Inhibiting Myristic Acid Uptake

“…NO is synthesized in endothelial cells by endothelial nitric-oxide synthase (eNOS), and eNOS in turn is activated by Akt-mediated phosphorylation of eNOS stimulated by VEGF signaling (18). Several studies have provided evidence that NO is an essential mediator of VEGF-stimulated angiogenesis (19,20). We found that NO-stimulated cGMP signaling in both endothelial and vascular smooth muscle cells is potently inhibited by picomolar concentrations of TSP1, its type 1 repeats, and CD36 antibodies (17,21) In endothelial cells, TSP1 blocked VEGF-stimulated cGMP synthesis.…”

“…NO is synthesized in endothelial cells by endothelial nitric-oxide synthase (eNOS), and eNOS in turn is activated by Akt-mediated phosphorylation of eNOS stimulated by VEGF signaling (18). Several studies have provided evidence that NO is an essential mediator of VEGF-stimulated angiogenesis (19,20 …”

Molecular Basis for the Regulation of Angiogenesis by Thrombospondin-1 and -2

“…VEGFA is an important driver of NO signaling via stimulation of eNOS (Murohara et al 1998;Fukumura et al 2001;Aicher et al 2003;Milkiewicz et al 2005;Yu et al 2005). By binding its receptor VEGFR2 on the endothelial cell surface, VEGFA induces parallel pathway (via both PI3K/AKT-1 and PLCg/AMPK pathways) phosphorylation of Ser-1177 on eNOS, which drives production of NO.…”

When bad things happen to good fish: the loss of hemoglobin and myoglobin expression in Antarctic icefishes

“…NO induces upregulation of one of the most potent factors influencing blood vessel proliferation, vascular endothelial growth factor (VEGF) (Kimura et al, 2000). Nitric oxide appears to play a role in both hypoxia-and exercise-induced stimulation of VEGF and angiogenesis in muscle (Milkiewicz et al, 2005;Kimura and Esumi, 2003). It is also noteworthy that VEGF, along with Angiopoietin-1 (Ang-1), promote enlargement of the lumenal diameter of the microvasculature (Suri et al, 1998).…”