Modulation of cAMP-Mediated Vasorelaxation by Endothelial Nitric Oxide and Basal cGMP in Vascular Smooth Muscle

Toyoshima, Hiroko; Nasa, Yoshihisa; Hashizume, Yoko; Koseki, Yumi; Isayama, Yoko; Kohsaka, Yumi; Yamada, Tomoko; Takeo, Satoshi

doi:10.1097/00005344-199810000-00006

Cited by 43 publications

(18 citation statements)

References 33 publications

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“…A relaxant response of rat aorta to cAMP-mediated vasodilators is regulated by NO production in endothelium and subsequent increase in cGMP in vascular smooth muscle cells. 37 We demonstrated doseand time-dependent effects of hydroxyurea on cGMP levels in HUVECs. Hydroxyurea induced cGMP levels within the first 30 minutes ( Figure 5B).…”

Section: Hydroxyurea Increased Camp and Cgmp Levels In Endothelial Cellsmentioning

confidence: 71%

Hydroxyurea induces the eNOS-cGMP pathway in endothelial cells

Čokić¹,

Beleslin-Čokić²,

Tomić³

et al. 2006

Blood

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Hydroxyurea is a cell-cycle-specific drug that has been used to treat myeloproliferative diseases and sickle cell anemia. We have recently shown that hydroxyurea, like nitric oxide (NO)-donor compounds, increased cGMP levels in human erythroid cells. We show now that hydroxyurea increases endothelial-cell production of NO; this induction of NO in human umbilical vein endothelial cells (HUVECs) and human bone marrow endothelial cell line (TrHBMEC) is blocked by competitive inhibitors of NO synthase (NOS), such as N G -nitro-L-arginine-methyl ester (L-NAME) and N G -nitro-L-arginine. It is dependent on cAMP-dependent protein kinase (PKA) and protein kinase B (PKB/Akt) activity. We found that hydroxyurea dose-and time-dependently induced rapid and transient phosphorylation of eNOS at Ser1177 in a PKA-dependent manner; inhibitors of PKB/Akt could partially abrogate this effect. In addition, hydroxyurea induced cAMP and cGMP levels in a dose-dependent manner, as well as levels of intracellular calcium in HUVECs. These studies established an additional mechanism by which rapid and sustained effects of hydroxyurea may affect cellular NO levels and perhaps enhance the effect of NO in myeloproliferative diseases. IntroductionHydroxyurea is a cytostatic agent (S-phase inhibitor) that has been used to treat erythrocytosis and thrombocytosis in polycythemia vera and other myeloproliferative diseases. 1 More recently, hydroxyurea demonstrated therapeutic benefit for sickle cell anemia by increasing fetal hemoglobin (HbF). 2 In addition to the known inhibition of ribonucleotide reductase, hydroxyurea can be oxidized by heme groups to produce nitric oxide (NO) in vivo (in rats) and in humans. 3,4 Hydroxyurea reacts with oxyHb and deoxyHb to form metHb, which then reacts with another hydroxyurea to form iron nitrosyl hemoglobin (HbNO). 5 The formation of HbNO involves the specific transfer of NO from the -NHOH group of hydroxyurea by a series of intermediate reactions. 3 Additionally, in vivo production of NO may result from the hydrolysis of hydroxyurea to hydroxylamine, followed by the rapid reactions of hydroxylamine with Hb. 6 It has been reported that hydroxyurea administration significantly increased NO x (NO metabolites nitrite and nitrate) and cGMP levels in plasma of sickle cell patients. 7 We have recently shown that hydroxyurea, like NO-donor compounds, increased cGMP levels contributing to gamma-globin gene expression in human erythroid cells. 8 Hydroxyurea is completely absorbed and elimination is through both renal and nonrenal mechanisms. 9 The metabolism of hydroxyurea to NO most likely occurs in the liver. 3 Chemical oxidation of hydroxyurea with a variety of oxidants, including copper(II) ions, produces NO. 9,10 Hydroxyurea-treated vascular endothelial cells showed significant morphologic changes such as an increase in apparent cell size, accompanied by an increase in cell Na and K contents. 11 During hydroxyurea treatment, cells accumulate in the late G1 to early S phase of the cell cycle. 12 Also, the level...

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Section: Hydroxyurea Increased Camp and Cgmp Levels In Endothelial Cellsmentioning

confidence: 71%

Hydroxyurea induces the eNOS-cGMP pathway in endothelial cells

Čokić¹,

Beleslin-Čokić²,

Tomić³

et al. 2006

Blood

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“…Evidence is mounting that ␤AR vasorelaxation is largely endotheliumdependent in a wide range of vascular districts that actively participate in the determination of total peripheral resistance, including skeletal muscle 2,22 and mesenteric 23 and pulmonary vasculature systems. 24 Furthermore, in vivo studies in cat hind limb, 25 canine coronary artery, 26 and newborn pial arteries 27 suggest that the endothelium dependency of ␤AR vasorelaxant responses is generalized. Finally, recent studies in humans indicate that endothelial ␤ARs are totally, or at least predominantly, of the ␤ 2 AR subtype.…”

Section: Discussionmentioning

confidence: 99%

β ₂ -Adrenergic Receptor Gene Delivery to the Endothelium Corrects Impaired Adrenergic Vasorelaxation in Hypertension

et al. 2002

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Background-Impaired ␤-adrenergic receptor (AR)-mediated vasorelaxation in hypertension plays a role in increased peripheral vascular resistance and blood pressure. Because the ␤ 2 AR is the most abundant vascular AR subtype, we sought to enhance ␤AR vasorelaxation by overexpressing ␤ 2 ARs via adenoviral-mediated gene transfer (AD␤ 2 AR) to the vascular endothelium of the carotid artery. Methods and Results-In normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats, we exposed the right common carotid artery to AD␤ 2 AR in situ for 15 minutes by injection into the lumen while the blood flow was interrupted. Control carotids received an empty vector (ADempty). Three days later, transgene expression and selective endothelial localization were confirmed in infected vessels. Vasoregulation after ␤ 2 AR overexpression (2-fold) was studied in isolated organ baths. AD␤ 2 AR carotid responses to ␣ 1 AR and ␣ 2 AR agonists were not affected, whereas responses to epinephrine were altered and ␤AR-mediated vasorelaxation was enhanced after ␤ 2 AR overexpression. As expected, ␤AR-mediated vasodilatation in control carotids of SHR rats was significantly less than in similar control WKY carotid arteries. AD␤ 2 AR treatment enhanced ␤AR vasorelaxation in SHR to levels similar to those seen in AD␤ 2 AR WKY carotids. Conclusions-Our results demonstrate a critical role for the endothelium in ␤AR-mediated vasorelaxation and suggest that impaired ␤AR signaling may account for dysfunctional ␤AR vasorelaxation in hypertension rather than impaired endothelium-dependent nitric oxide metabolism.

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“…It is believed that cAMP and cGMP stimulate their associated protein kinases, PKA and PKG, respectively, but recent evidence suggests that the vasodilatory effects of cAMP-producing agents may involve "cross-activation" of PKG by cAMP (41,43) and stimulation of PKA by cGMP (8). Lincoln and colleagues (24) originally showed that cross-activation of PKG by cAMP was important in cAMP-elevating agent vasodilatation, and it is thought that cAMP can activate both PKA and PKG.…”

mentioning

confidence: 99%

“…Lincoln and colleagues (24) originally showed that cross-activation of PKG by cAMP was important in cAMP-elevating agent vasodilatation, and it is thought that cAMP can activate both PKA and PKG. However, relaxation correlates most closely with PKG activation (13), and vasodilators that increase cGMP and cAMP seem to act synergistically on vasorelaxation (41). Thus, whereas studies have reported the existence of cross-activation of PKG by cAMP, few studies have investigated this signaling mechanism at the cellular and molecular levels in pulmonary arterial smooth muscle cells (PASMC).…”

mentioning

confidence: 99%

cAMP activates BK_Cachannels in pulmonary arterial smooth muscle via cGMP-dependent protein kinase

Barman

Zhu

White

2003

American Journal of Physiology-Lung Cellular and Molecular Phys

103

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Barman, Scott A., Shu Zhu, Guichan Han, and Richard E. White. cAMP activates BK Ca channels in pulmonary arterial smooth muscle via cGMP-dependent protein kinase. Am J Physiol Lung Cell Mol Physiol 284: L1004-L1011, 2003. First published January 24, 2003 10.1152/ajplung.00295. 2002The signal transduction mechanisms defining the role of cyclic nucleotides in the regulation of pulmonary vascular tone is currently an area of great interest. Normally, signaling mechanisms that elevate cAMP and guanosine-3Ј,5Ј-cyclic monophosphate (cGMP) maintain the pulmonary vasculature in a relaxed state. Modulation of the largeconductance, calcium-and voltage-activated potassium (BK Ca) channel is important in the regulation of pulmonary arterial pressure, and inhibition (closing) of the BK Ca channel has been implicated in the development of pulmonary hypertension. Accordingly, studies were done to determine the effect of cAMP-elevating agents on BK Ca channel activity using patch-clamp studies in pulmonary arterial smooth muscle cells (PASMC) of the fawn-hooded rat (FHR), a recognized animal model of pulmonary hypertension. Forskolin (10 M), a stimulator of adenylate cyclase and an activator of cAMP-dependent protein kinase (PKA), and 8-4-chlorophenylthio (CPT)-cAMP (100 M), a membrane-permeable derivative of cAMP, opened BK Ca channels in single FHR PASMC. Treatment of FHR PASMC with 300 nM KT5823, a selective inhibitor of cGMP-dependent protein kinase (PKG) activity inhibited the effect of both forskolin and CPT-cAMP. In contrast, blocking PKA activation with 300 nM KT5720 had no effect on forskolin or CPT-cAMP-stimulated BKCa channel activity. These results indicate that cAMP-dependent vasodilators activate BKCa channels in PASMC of FHR via PKG-dependent and PKA-independent signaling pathways, which suggests cross-activation between cyclic nucleotide-dependent protein kinases in pulmonary arterial smooth muscle and therefore, a unique signaling pathway for cAMP-induced pulmonary vasodilation.high-conductance calcium-and voltage-activated potassium channel; cAMP-dependent protein kinase; cross-activation SIGNAL TRANSDUCTION MECHANISMS defining the role of cyclic nucleotides in the modulation of vascular tone is currently an area of great interest. Agents that relax vascular smooth muscle via activation of adenylate cyclase, such as forskolin, are thought to elicit their biological effects by increasing the intracellular concentration of cAMP (16,17,34). Although the exact mechanism by which cAMP causes vascular relaxation is not known, it is believed that activation of PKA is involved (7,17,18). In addition to cAMP-mediated vascular relaxation, guanosine-3Ј,5Ј-cyclic monophosphate (cGMP) has been reported to elicit vasodilatation by activation of cGMP-dependent PKG (6, 23). In the pulmonary circulation, cGMP and cAMP have been implicated as mediators of smooth muscle vasodilatation (13,15,16,24), and in ovine pulmonary vascular smooth muscle, it has recently been reported that pulmonary arteries are more sensitive to relaxa...

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Modulation of cAMP-Mediated Vasorelaxation by Endothelial Nitric Oxide and Basal cGMP in Vascular Smooth Muscle

Cited by 43 publications

References 33 publications

Hydroxyurea induces the eNOS-cGMP pathway in endothelial cells

Hydroxyurea induces the eNOS-cGMP pathway in endothelial cells

β ₂ -Adrenergic Receptor Gene Delivery to the Endothelium Corrects Impaired Adrenergic Vasorelaxation in Hypertension

cAMP activates BK_Cachannels in pulmonary arterial smooth muscle via cGMP-dependent protein kinase

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Modulation of cAMP-Mediated Vasorelaxation by Endothelial Nitric Oxide and Basal cGMP in Vascular Smooth Muscle

Cited by 43 publications

References 33 publications

Hydroxyurea induces the eNOS-cGMP pathway in endothelial cells

Hydroxyurea induces the eNOS-cGMP pathway in endothelial cells

β 2 -Adrenergic Receptor Gene Delivery to the Endothelium Corrects Impaired Adrenergic Vasorelaxation in Hypertension

cAMP activates BKCachannels in pulmonary arterial smooth muscle via cGMP-dependent protein kinase

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β ₂ -Adrenergic Receptor Gene Delivery to the Endothelium Corrects Impaired Adrenergic Vasorelaxation in Hypertension

cAMP activates BK_Cachannels in pulmonary arterial smooth muscle via cGMP-dependent protein kinase