Nitric Oxide Stimulates Vascular Endothelial Growth Factor Production in Cardiomyocytes Involved in Angiogenesis

Abstract

Background: Hypoxia-inducible factor (HIF)-1α regulates the transcription of lines of genes, including vascular endothelial growth factor (VEGF), a major gene responsible for angiogenesis. Several recent studies have demonstrated that a nonhypoxic pathway via nitric oxide (NO) is involved in the activation of HIF-1α. However, there is no direct evidence demonstrating the release of angiogenic factors by cardiomyocytes through the nonhypoxic induction pathway of HIF-1α in the heart. Therefore we assessed the effects of an NO donor, S-Nitroso-N-acetylpenicillamine (SNAP) on the induction of VEGF via HIF-1α under normoxia, using primary cultured rat cardiomyocytes (PRCMs). Methods and Results: PRCMs treated with acetylcholine (ACh) or SNAP exhibited a significant production of NO. SNAP activated the induction of HIF-1α protein expression in PRCMs during normoxia. Phosphatidylinositol 3-kinase (PI3K)-dependent Akt phosphorylation was induced by SNAP and was completely blocked by wortmannin, a PI3K inhibitor, and N G -nitro-L-arginine methyl ester (L-NAME), a NO synthase inhibitor. The SNAP treatment also increased VEGF protein expression in PRCMs. Furthermore, conditioned medium derived from SNAP-treated cardiomyocytes phosphorylated the VEGF type-2 receptor (Flk-1) of human umbilical vein endothelial cells (a fourfold increase compared to the control group, p < 0.001, n = 5) and accelerated angiogenesis. Conclusion: Our results suggest that cardiomyocytes produce VEGF through a nonhypoxic HIF-1α induction pathway activated by NO, resulting in angiogenesis.

Donepezil Can Improve Ischemic Muscle Atrophy by Activating Angiomyogenic Properties of Satellite Cells

“…However, as with the previous study by Kuwabara et al, 26 we speculate that a muscle-derived angiogenic factor plays an important role in the hindlimb ischemia model, which is also supported by Tateno K et al 11 Therefore, we speculate that DPZ could inhibit skeletal muscle loss in hindlimb ischemia to sustain muscle volume and stimulate myogenesis through increased Pax7-positive cells, both resulting in activation of the angiogenic mechanism of skeletal muscle, that is, satellite cells. Because the DPZ effects appear evident within the first week, much earlier than the time point when a non-treated ischemic hindlimb shows a nadir of subjected skin temperature, this result also suggests that DPZ salvages skeletal muscle and accelerates angiogenesis.…”

Donepezil, an acetylcholinesterase inhibitor against Alzheimer's dementia, promotes angiogenesis in an ischemic hindlimb model

“…Specifically, donepezil activated protein expression of VEGF and ChAT, a critical enzyme for de novo ACh synthesis, accelerated endothelial cell proliferation, and inhibited apoptosis, partly independent of cholinergic receptors. These results suggest that donepezil regulates angiogenesis through a non-hypoxic HIF-1 induction pathway, which might be triggered by increased ACh [3,4]. Donepezil was developed to treat patients with Alzheimer's disease as an acetylcholinesterase inhibitor [12,13].…”

“…Specifically, according to our previous study, the NO donor S-nitroso-N-acetylpenicillamine activates the PI3K/Akt/HIF-1 pathway to increase VEGF expression in cardiomyocytes, and VEGF derived from cardiomyocytes accelerates tube formation in human umbilical endothelial cells (HUVECs), i.e., in vitro angiogenesis [4].…”

The functional nitrite reductase activity of the heme-globins

“…37,54 In tissues such as the heart, liver, brain, and aorta the nitrite levels (0.5-10 M) 81,82 are greater than in blood (0.12-0.13 M) 83 and NO is known to regulate several hypoxic cell signaling responses including mitochondrial respiration and biogenesis, [84][85][86][87][88] expression of hypoxia inducible factor-1 (HIF-1␣), 89,90 and angiogenesis. [91][92][93] In these tissues, the reduction of nitrite may provide a mechanism by which NO is generated during hypoxia, when NO synthase becomes oxygen limited. Oxygen is a requisite substrate for the production of NO by nitric oxide synthase (K m ϭ 100 M; note exact value for NOS K m for oxygen is highly variable in the published literature), 94 so in normoxic conditions, oxygen is used by NOS for NO generation.…”