Role of 20-hydroxyeicosatetraenoic acid in the renal and vasoconstrictor actions of angiotensin II

2002 ◽  
Vol 283 (1) ◽  
pp. R60-R68 ◽  
Author(s):  
Magdalena Alonso-Galicia ◽  
Kristopher G. Maier ◽  
Andrew S. Greene ◽  
Allen W. Cowley ◽  
Richard J. Roman
Keyword(s):  
Urinary Excretion ◽  
Intravenous Infusion ◽  
Pressor Response ◽  
Maximal Response ◽  
Epoxyeicosatrienoic Acids ◽  
Ang Ii ◽  
Hydroxyeicosatetraenoic Acid ◽  
Peripheral Vasculature ◽  
Oxide Synthase

The present study examined the effects of ANG II on the renal synthesis of 20-hydroxyeicosatetraenoic acid (20-HETE) and its contribution to the renal vasoconstrictor and the acute and chronic pressor effects of ANG II in rats. ANG II (10−11 to 10−7mol/l) reduced the diameter of renal interlobular arteries treated with inhibitors of nitric oxide synthase and cyclooxygenase, lipoxygenase, and epoxygenase by 81 ± 8%. Subsequent blockade of the synthesis of 20-HETE with 17-octadecynoic acid (1 μmol/l) increased the ED50 for ANG II-induced constriction by a factor of 15 and diminished the maximal response by 61%. Graded intravenous infusion of ANG II (5–200 ng/min) dose dependently increased mean arterial pressure (MAP) in thiobutylbarbitol-anesthetized rats by 35 mmHg. Acute blockade of the formation of 20-HETE with dibromododecenyl methylsulfimide (DDMS; 10 mg/kg) attenuated the pressor response to ANG II by 40%. An intravenous infusion of ANG II (50 ng · kg−1 · min−1) in rats for 5 days increased the formation of 20-HETE and epoxyeicosatrienoic acids (EETs) in renal cortical microsomes by 60 and 400%, respectively, and increased MAP by 78 mmHg. Chronic blockade of the synthesis of 20-HETE with intravenous infusion of DDMS (1 mg · kg−1 · h−1) or EETs and 20-HETE with 1-aminobenzotriazole (ABT; 2.2 mg · kg−1 · h−1) attenuated the ANG II-induced rise in MAP by 40%. Control urinary excretion of 20-HETE averaged 350 ± 23 ng/day and increased to 1,020 ± 105 ng/day in rats infused with ANG II (50 ng · kg−1 · min−1) for 5 days. In contrast, urinary excretion of 20-HETE only rose to 400 ± 40 and 600 ± 25 ng/day in rats chronically treated with ANG II and ABT or DDMS respectively. These results suggest that acute and chronic elevations in circulating ANG II levels increase the formation of 20-HETE in the kidney and peripheral vasculature and that 20-HETE contributes to the acute and chronic pressor effects of ANG II.

scholarly journals Contribution of epoxyeicosatrienoic acids to flow-induced dilation in arteries of male ERα knockout mice: role of aromatase

2007 ◽  
Vol 293 (3) ◽  
pp. R1239-R1246 ◽  
Author(s):  
Dong Sun ◽  
Changdong Yan ◽  
Azita Jacobson ◽  
Houli Jiang ◽  
Mairead A. Carroll ◽  
...  
Keyword(s):  
Gas Chromatography Mass Spectrometry ◽  
Epoxyeicosatrienoic Acids ◽  
Epoxyeicosatrienoic Acid ◽  
Wild Type ◽  
Electrophysiological Technique ◽  
Isolated Arteries ◽  
Oxide Synthase ◽  
Interfering Rna ◽  
Endothelial Nitric Oxide

We studied the roles of estrogen receptors (ER) and aromatase in the mediation of flow-induced dilation (FID) in isolated arteries of male ERα-knockout (ERα-KO) and wild-type (WT) mice. FID was comparable between gracilis arteries of WT and ERα-KO mice. In WT arteries, inhibition of NO and prostaglandins eliminated FID. In ERα-KO arteries, Nω-nitro-l-arginine methyl ester (l-NAME) inhibited FID by ∼26%, whereas indomethacin inhibited dilations by ∼50%. The remaining portion of the dilation was abolished by additional administration of 6-(2-proparglyoxyphenyl)hexanoic acid (PPOH) or iberiotoxin, inhibitors of epoxyeicosatrienoic acid (EET) synthesis and large-conductance potassium channels, respectively. By using an electrophysiological technique, we found that, in the presence of 10 dyne/cm2 shear stress, perfusate passing through donor vessels isolated from gracilis muscle of ERα-KO mice subjected to l-NAME and indomethacin elicited smooth muscle hyperpolarization and a dilator response of endothelium-denuded detector vessels. These responses were prevented by the presence of iberiotoxin in detector or PPOH in donor vessels. Gas chromatography-mass spectrometry (GC-MS) analysis indicated a significant increase in arterial production of EETs in ERα-KO compared with WT mice. Western blot analysis showed a significantly reduced endothelial nitric oxide synthase expression but enhanced expressions of aromatase and ERβ in ERα-KO arteries. Treatment of ERα-KO arteries with specific aromatase short-interfering RNA for 72 h, knocked down the aromatase mRNA and protein associated with elimination of EET-mediation of FID. Thus, FID in male ERα-KO arteries is maintained via an endothelium-derived hyperpolarizing factor/EET-mediated mechanism compensating for reduced NO mediation due, at least in part, to estrogen aromatized from testosterone.

Abstract P152: Aminopeptidase A in the Brain Exerts Cardiovascular Action via Degradation of Kallidin to Bradykinin

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Takuto Nakamura ◽  
Masanobu Yamazato ◽  
Yusuke Ohya
Keyword(s):  
Blood Pressure ◽  
Pressor Response ◽  
Cardiovascular Regulation ◽  
Receptor Blocker ◽  
Ang Ii ◽  
Aminopeptidase A ◽  
Hoe 140 ◽  
Wistar Kyoto ◽  
The Brain

Objective: Aminopeptidase A (APA) degrades of various sympathomodulatory peptides such as angiotensin (Ang) II, cholecystkinin-8, neurokinin B and kallidin. APA activity is increased in the brain of hypertensive rats. A centrally acting APA inhibitor prodrug is currently under investigation in clinical trial for treatment of hypertension. In previous reports, a role of APA in the brain on cardiovascular regulation was researched focus on only renin-angiotensin system. We previously reported that intracerebroventricular(icv) administration of APA increased blood pressure and that this pressor response was partially blocked by angiotensin receptor blocker. In this study, we evaluated a role of APA on cardiovascular regulation focusing on peptides other than Ang II. Method: Eleven weeks old Wistar Kyoto rats were used. We icv administrated 800 ng/8 μL of APA after pretreatment of following drugs, i) 8μL of artificial cerebrospinal fluid (aCSF) as a control, ii) 80 nmol/8 μL of amastatin which is a non-specific aminopeptidase inhibitor, iii) 1 nmol/8 μL of HOE-140 which is a bradykinin receptor blocker to evaluate the involvement of degradation of kallidin to bradykinin by APA. Result: i) Icv administration of APA after pretreatment of aCSF increased blood pressure rapidly. Blood pressure reached a peak within 1 minute. The elevated blood pressure decreased gradually and reached baseline blood pressure in 10 minutes. A peak pressor response is 25.5±1.4 mmHg (n=5). ii) Icv pretreatment of amastatin or HOE-140 did not change the blood pressure. A peak pressor response induced by APA is 13.1±4.1 mmHg (n=6, p<0.05 vs aCSF). iii) Icv pretreatment of HOE-140 did not change the blood pressure. A peak pressor response induced by APA is 21.2±1.8 mmHg (n=4, p<0.05 vs aCSF). Conclusion: 1) Icv administration of APA increased blood pressure by APA enzymatic activity. 2) Cardiovascular regulation of APA in the brain is due to not only degradation of Ang II to Ang III but also degradation of kallidin to bradykinin. Clinical implication: We think inhibition of APA in the brain may be a unique therapeutic target which affects several cardiovascular peptides in the brain.

Role of superoxide anion in regulating pressor and vascular hypertrophic response to angiotensin II

2002 ◽  
Vol 282 (5) ◽  
pp. H1697-H1702 ◽  
Author(s):  
Hui Di Wang ◽  
Douglas G. Johns ◽  
Shanqin Xu ◽  
Richard A. Cohen
Keyword(s):  
Superoxide Anion ◽  
Pressor Response ◽  
Cross Sectional Area ◽  
Ang Ii ◽  
Sectional Area ◽  
Wild Type ◽  
Cross Sectional ◽  
Hypertrophic Response

Our purpose was to address the role of NAPDH oxidase-derived superoxide anion in the vascular response to ANG II. Blood pressure, aortic superoxide anion, 3-nitrotyrosine, and medial cross-sectional area were compared in wild-type mice and in mice that overexpress human superoxide dismutase (hSOD). The pressor response to ANG II was significantly less in hSOD mice. Superoxide anion levels were increased twofold in ANG II-treated wild-type mice but not in hSOD mice. 3-Nitrotyrosine increased in aortic endothelium and adventitia in wild-type but not hSOD mice. In contrast, aortic medial cross-sectional area increased 50% with ANG II in hSOD mice, comparable to wild-type mice. The lower pressor response to ANG II in the mice expressing hSOD is consistent with a pressor role of superoxide anion in wild-type mice, most likely because it reacts with nitric oxide. Despite preventing the increase in superoxide anion and 3-nitrotyrosine, the aortic hypertrophic response to ANG II in vivo was unaffected by hSOD.

Angiotensin II decreases inducible nitric oxide synthase expression in rat astroglial cultures

1995 ◽  
Vol 268 (3) ◽  
pp. C700-C707 ◽  
Author(s):  
L. J. Chandler ◽  
K. Kopnisky ◽  
E. Richards ◽  
F. T. Crews ◽  
C. Sumners
Keyword(s):  
Nitric Oxide ◽  
Angiotensin Ii ◽  
Nitric Oxide Synthase ◽  
Receptor Antagonist ◽  
Maximal Response ◽  
No Production ◽  
Dependent Manner ◽  
Ang Ii ◽  
Subsequent Formation ◽  
Oxide Synthase

Consistent with stimulation of expression of an inducible form of nitric oxide synthase (iNOS), exposure of rat astroglial cultures to lipopolysaccharide (LPS) caused a time-dependent increase in the accumulation of nitrite in the culture media. Addition of the peptide angiotensin II (ANG II) with LPS decreased subsequent formation of nitrite in a concentration-dependent manner (concentration inhibiting 50% of maximal response approximately 1 nM). The ANG II effect could be blocked by the ANG II type 1 (AT1 receptor antagonist losartan but not by the ANG II type 2 (AT2) receptor antagonist PD-123177. ANG II had no effect on nitrite formation stimulated by a combination of inflammatory cytokines (interleukin-1 beta, tumor necrosis factor-alpha, and interferon-gamma). A brief 10-min exposure to ANG II was sufficient to cause an approximately 30% inhibition of the LPS response, with maximal inhibition of approximately 65% after 3 h, and occurred only when ANG II was added during the iNOS induction phase. Consistent with partial inhibition of LPS-stimulated expression of iNOS, ANG II reduced the levels of both iNOS mRNA and iNOS protein. These results demonstrate that ANG II can decrease LPS-stimulated NO production in astroglia by inhibiting induction of iNOS expression.

Role of periaqueductal gray in the pressor response produced by central injections of angiotensin II

1993 ◽  
Vol 265 (5) ◽  
pp. R1052-R1059
Author(s):  
L. R. Portis ◽  
S. J. Lewis ◽  
M. J. Brody
Keyword(s):  
Electrical Stimulation ◽  
Angiotensin Ii ◽  
Fluorescent Dyes ◽  
Pressor Response ◽  
Periaqueductal Gray ◽  
Ang Ii ◽  
Hemodynamic Responses ◽  
Anesthetized Rats ◽  
Stimulation Of

The present studies were undertaken to determine the role of rostral periaqueductal gray (PAG) in mediating the pressor effect produced by intracerebroventricular (icv) injection of angiotensin II (ANG II, 200 ng). Two functionally and anatomically distinct sites were identified in rostral PAG: a dorsomedial site involved in the hemodynamic responses produced by electrical stimulation of the anteroventral third ventricle (AV3V) region and a ventromedial site required for the pressor response elicited by icv administration of ANG II. In Saffan-anesthetized rats, injection of lidocaine (LIDO, 4%) in dorsomedial PAG, but not in ventromedial PAG, significantly attenuated the decrease in hindquarter resistance (HQR) produced by electrical stimulation of the AV3V region, and the poststimulatory increase in mean arterial pressure (MAP) and HQR. The injection of LIDO in ventromedial PAG had no effect on the hemodynamic responses produced by electrical stimulation of the AV3V region in anesthetized rats but significantly attenuated the pressor response produced by icv administration of ANG II in conscious rats. The hypothesis that these two sites receive separate projections was addressed by microinjecting two retrogradely transported fluorescent dyes, Fluoro-Gold and Fast Blue. The anatomic findings suggest that separation of the pathways activated by electrical and chemical stimulation of the AV3V region occurs at the level of rostral PAG.

scholarly journals Activation of mTOR/p70S6 kinase by ANG II inhibits insulin-stimulated endothelial nitric oxide synthase and vasodilation

2012 ◽  
Vol 302 (2) ◽  
pp. E201-E208 ◽  
Author(s):  
Jeong-a Kim ◽  
Hyun-Ju Jang ◽  
Luis A. Martinez-Lemus ◽  
James R. Sowers
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Vascular Endothelium ◽  
Endothelial Nitric Oxide Synthase ◽  
Point Mutations ◽  
Ang Ii ◽  
Cardiovascular Tissues ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

Elevated tissue levels of angiotensin II (ANG II) are associated with impairment of insulin actions in metabolic and cardiovascular tissues. ANG II-stimulated activation of mammalian target of rapamycin (mTOR)/p70 S6 kinase (p70S6K) in cardiovascular tissues is implicated in cardiac hypertrophy and vascular remodeling. However, the role of ANG II-stimulated mTOR/p70S6K in vascular endothelium is poorly understood. In the present study, we observed that ANG II stimulated p70S6K in bovine aortic endothelial cells. ANG II increased phosphorylation of insulin receptor substrate-1 (IRS-1) at Ser636/639 and inhibited the insulin-stimulated phosphorylation of endothelial nitric oxide synthase (eNOS). An inhibitor of mTOR, rapamycin, attenuated the ANG II-stimulated phosphorylation of p70S6K and phosphorylation of IRS-1 (Ser636/639) and blocked the ability of ANG II to impair insulin-stimulated phosphorylation of eNOS, nitric oxide production, and mesenteric-arteriole vasodilation. Moreover, point mutations of IRS-1 at Ser636/639 to Ala prevented the ANG II-mediated inhibition of insulin signaling. From these results, we conclude that activation of mTOR/p70S6K by ANG II in vascular endothelium may contribute to impairment of insulin-stimulated vasodilation through phosphorylation of IRS-1 at Ser636/639. This ANG II-mediated impairment of vascular actions of insulin may help explain the role of ANG II as a link between insulin resistance and hypertension.

Role of the renal kinin-prostaglandin system in diltiazem-induced natriuresis

1986 ◽  
Vol 250 (2) ◽  
pp. F197-F202
Author(s):  
M. Seino ◽  
K. Abe ◽  
N. Nushiro ◽  
K. Omata ◽  
K. Sato ◽  
...  
Keyword(s):  
Urinary Excretion ◽  
Significant Relationship ◽  
Intravenous Infusion ◽  
Renal Hemodynamics ◽  
Prostaglandin E ◽  
Drug Induced ◽  
Entry Blocker ◽  
Prostaglandin System

Intravenous infusion of the Ca2+ entry blocker diltiazem (10 micrograms . kg-1 . min-1 for 30 min) induced an increase in urinary excretion of sodium (UNaV) from 209 +/- 42 to 922 +/- 311 mueq without significant alterations in renal hemodynamics in anesthetized rabbits. Urinary excretion of kinin (UkinV) and prostaglandin E (UPGEV) were also increased by diltiazem, from 14.3 +/- 2.5 to 25.9 +/- 4.8 ng and 1.33 +/- 0.20 to 2.44 +/- 0.34 ng, respectively. Moreover, there was a significant correlation between UkinV and UNaV (r = 0.81, P less than 0.05). A significant relationship between UPGEV and UNaV (r = 0.83, P less than 0.05) was also observed. However, no correlation between urinary excretion of kallikrein (UkallV) and UNaV was found after infusion of diltiazem. Further, to examine a possible contribution of renal kinins and prostaglandins in diltiazem-induced natriuresis, aprotinin (50,000 KIU/kg bolus + 1,000 KIU . kg-1 . min-1 infusion) and indomethacin (8 mg/kg) were used. Aprotinin pretreatment attenuated diltiazem-induced natriuresis, accompanied by suppression of UkallV, UkinV, and UPGEV. However, indomethacin pretreatment did not affect this drug-induced natriuresis, although UPGEV was significantly decreased. Furthermore, under the indomethacin pretreatment, a significant increase in UkinV was produced by diltiazem. These results suggest that renal kinins rather than renal prostaglandin E, at least in part, play a role in diltiazem-induced natriuresis.

scholarly journals AKT phosphorylation is essential for insulin-induced relaxation of rat vascular smooth muscle cells

2006 ◽  
Vol 291 (6) ◽  
pp. C1355-C1365 ◽  
Author(s):  
Jin Hee Lee ◽  
Louis Ragolia
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Glycogen Synthase ◽  
Ang Ii ◽  
Akt Phosphorylation ◽  
Akt Activation ◽  
Oxide Synthase ◽  
Constitutively Active

Insulin resistance, a major factor in the development of type 2 diabetes, is known to be associated with defects in blood vessel relaxation. The role of Akt on insulin-induced relaxation of vascular smooth muscle cell (VSMC) was investigated using siRNA targeting Akt (siAKTc) and adenovirus constructing myristilated Akt to either suppress endogenous Akt or overexpress constitutively active Akt, respectively. siAKTc decreased both basal and insulin-induced phosphorylations of Akt and glycogen synthase kinase 3β, abolishing insulin-induced nitric oxide synthase (iNOS) expression. cGMP-dependent kinase 1α (cGK1α) and myosin-bound phosphatase (MBP) activities, both downstream of iNOS, were also decreased. siAKTc treatment resulted in increased insulin and ANG II-stimulated phosphorylation of contractile apparatus, such as MBP substrate (MYPT1) and myosin light chain (MLC20), accompanied by increased Rho-associated kinase α (ROKα) activity, demonstrating the requirement of Akt for insulin-induced vasorelaxation. Corroborating these results, constitutively active Akt upregulated the signaling molecules involved in insulin-induced relaxation such as iNOS, cGK1α, and MBP activity, even in the absence of insulin stimulation. On the contrary, the contractile response involving the phosphorylation of MYPT1 and MLC20, and increased ROKα activity stimulated by ANG II were all abolished by overexpressing active Akt. In conclusion, we demonstrated here that insulin-induced VSMC relaxation is dependent on Akt activation via iNOS, cGK1α, and MBP activation, as well as the decreased phosphorylations of MYPT1 and MLC20 and decreased ROKα activity.

Nitric oxide activity in the peripheral vasculature during normotensive and preeclamptic pregnancy

1999 ◽  
Vol 277 (2) ◽  
pp. H848-H854 ◽  
Author(s):  
Dilly O. C. Anumba ◽  
Stephen C. Robson ◽  
Richard J. Boys ◽  
Gary A. Ford
Keyword(s):  
Nitric Oxide ◽  
Forearm Blood Flow ◽  
Peripheral Resistance ◽  
Normal Pregnancy ◽  
Ang Ii ◽  
Third Trimester ◽  
Peripheral Vasculature ◽  
Infusion Of Norepinephrine ◽  
Synthase Inhibitor

We investigated the role of nitric oxide (NO) in the vascular resistance changes of normotensive and preeclamptic pregnancy. Forearm blood flow (FBF) responses to brachial artery infusion of N G-monomethyl-l-arginine (l-NMMA), an NO synthase inhibitor, and angiotensin II (ANG II), an NO-independent vasoconstrictor, were determined by plethysmography in 20 nonpregnant women, 20 normotensive primigravidae, and 15 primigravidae with untreated preeclampsia. In pregnant subjects, FBF was reduced to nonpregnancy levels by infusion of norepinephrine (NE), which was then coinfused with ANG II (2, 4, and 8 ng/min) and l-NMMA (200, 400, and 800 μg/min) each for 5 min. In separate studies, responses to NE (20, 50, and 100 ng/min) were determined in 8 nonpregnant women, with FBF elevated to pregnancy levels by concomitant infusion of glyceryl trinitrate, and 10 pregnant women. Vasoconstrictor responses tol-NMMA were increased in pregnant compared with nonpregnant subjects [mean ± SE summary measure (in arbitrary units): 60 ± 7 vs. 89 ± 8, respectively; P < 0.01], whereas responses to ANG II were blunted (125 ± 11 vs. 79 ± 7, respectively; P < 0.001). Compared with normotensive pregnant subjects, preeclamptic subjects had an enhanced response to ANG II (79 ± 7 vs. 103 ± 8, respectively; P < 0.05) but no difference in response to l-NMMA (89 ± 8 vs. 73 ± 10, respectively; P = 0.30). Responses to NE were similar in pregnant and nonpregnant subjects (110 ± 20 vs. 95 ± 33, respectively; P = 0.66). During the third trimester of pregnancy, forearm constrictor responses tol-NMMA are increased. The responses to NE are unchanged, whereas responses to ANG II are blunted. Increased NO activity contributes to the fall in peripheral resistance. In preeclampsia, forearm constrictor responses to ANG II but notl-NMMA are increased compared with those in normal pregnancy. Changes in vascular NO activity are unlikely to account for the increased vascular tone in this condition.

Pressor responsiveness in pseudopregnant and pregnant rats: role of maternal factors

1989 ◽  
Vol 257 (4) ◽  
pp. R866-R871 ◽  
Author(s):  
M. S. Paller ◽  
G. Gregorini ◽  
T. F. Ferris
Keyword(s):  
Vascular Reactivity ◽  
Pressor Response ◽  
Ang Ii ◽  
Maternal Factors ◽  
Synthesis Inhibitor ◽  
Pregnant Rats ◽  
Plasma Progesterone ◽  
Early Increase ◽  
In Pregnancy

During pregnancy the pressor response to vasoconstrictor substances such as angiotensin II (ANG II) is diminished, and renal, uterine, and vascular prostaglandin (PG) production may increase. However, little is known about the factors that alter vascular reactivity or stimulate PG synthesis during pregnancy. To ascertain whether these factors are of maternal or fetal-placental origin, we studied vascular reactivity and urinary PGE excretion in pseudopregnant rats. Pseudopregnant rats had plasma progesterone and weight gain similar to that observed in pregnant rats. Urinary PG excretion in nonpregnant rats was approximately 70 ng/24 h and remained constant during a 12-day observation. In contrast, urinary PG excretion in both pregnant and in pseudopregnant rats rose to levels approximately twice control within 4-6 days. The pressor response to ANG II was diminished in pseudopregnant rats compared with nonpregnant rats. When the PG synthesis inhibitor meclofenamate was given there was no change in the pressor response to ANG II in nonpregnant animals, but in pseudopregnant animals meclofenamate produced a significant increase in the pressor response to ANG II. The pressor response to norepinephrine and arginine vasopressin (AVP) was not diminished in pseudopregnant animals, and meclofenamate did not increase the pressor response to these agents. Therefore, a developing fetus and placenta is not necessary for the decrease in pressor response to ANG II nor for the early increase in urinary PGE excretion. Like in pregnancy, the pressor response to ANG II was increased after meclofenamate in pseudopregnancy. Increased PG production may, therefore, be partly responsible for the decrease in pressor responsiveness to ANG II. However, pseudopregnancy, unlike pregnancy, did not affect pressor responsiveness to norepinephrine or AVP. Both maternal and fetal-placental factors seem required for the reduction in responsiveness to norepinephrine and AVP in pregnancy.

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