Role of reactive oxygen species and NAD(P)H oxidase in α₁-adrenoceptor signaling in adult rat cardiac myocytes

Abstract

We recently reported that alpha(1)-adrenoceptor (alpha(1)-AR) stimulation induces hypertrophy via activation of the mitogen/extracellular signal-regulated kinase (MEK) 1/2-extracellular signal-regulated kinase (ERK) 1/2 pathway and generates reactive oxygen species (ROS) in adult rat ventricular myocytes (ARVM). Here we investigate the intracellular source of ROS in ARVM and the mechanism by which ROS activate hypertrophic signaling after alpha(1)-AR stimulation. Pretreatment of ARVM with the ROS scavenger Mn(III)terakis(1-methyl-4-pyridyl) porphyrin pentachloride (MnTMPyP) completely inhibited the alpha(1)-AR-stimulated activation of Ras-MEK1/2-ERK1/2. Direct addition of H(2)O(2) or the superoxide generator menadione activated ERK1/2, which is also prevented by MnTMPyP pretreatment. We found that ARVM express gp91(phox), p22(phox), p67(phox), and p47(phox), four major components of NAD(P)H oxidase, and that alpha(1)-AR-stimulated ERK1/2 activation was blocked by four structurally unrelated inhibitors of NAD(P)H oxidase [diphenyleneiodonium, phenylarsine oxide, 4-(2-aminoethyl)benzenesulfonyl fluoride, and cadmium]. Conversely, inhibitors for other potential ROS-producing systems, including mitochondrial electron transport chain, nitric oxide synthase, xanthine oxidase, and cyclooxygenase, had no effect on alpha(1)-AR-stimulated ERK1/2 activation. Taken together, our results show that ventricular myocytes express components of an NAD(P)H oxidase that appear to be involved in alpha(1)-AR-stimulated hypertrophic signaling via ROS-mediated activation of Ras-MEK1/2-ERK1/2.

Homocysteine-induced cardiomyocyte apoptosis and plasma membrane flip-flop are independent of S-adenosylhomocysteine: a crucial role for nuclear p47phox

“…The NOX complex subunits p22 phox , gp91 phox (NOX2), p67 phox , and p47 phox have been identified in cardiomyocytes [15][16][17]. Previously, we have shown that Hcy induced apoptosis in cardiomyocytes through a nuclear NOX2-mediated ROS production mechanism and also induced membrane flipflop and necrosis [18].…”

Is Cardiac Hypertrophy in Spontaneously Hypertensive Rats the Cause or the Consequence of Oxidative Stress?

“…The oxidative stress is the result of an increase of reactive oxygen species (ROS) production and/or inadequate antioxidant defense mechanisms. It has been shown that an increase in the activity and expression of myocardial NAD(P)H oxidase is the main source of ROS in cardiac hypertrophy (5)(6)(7). However, existing data about the antioxidant status in hypertension are inconsistent.…”

Pivotal Role of gp91 phox -Containing NADH Oxidase in Lipopolysaccharide-Induced Tumor Necrosis Factor-α Expression and Myocardial Depression

“…On stimulation, the cytosolic component p47 phox becomes phosphorylated, and the cytosolic complex migrates to the membrane, where it binds to cytochrome b558 to assemble into an active oxidase. 7 NAD(P)H oxidase expression has also been demonstrated in cardiomyocytes 8,9 and has been considered as a critical determinant of the redox state of the myocardium. 8 -11 In response to LPS, NAD(P)H oxidase activity and O 2 Ϫ production are markedly increased in the heart 12,13 ; however, the contribution of the NADH oxidase to TNF-␣ expression in LPS-stimulated cardiomyocytes remains unknown, and the role of NADH oxidase in septic myocardial depression has not been investigated.…”