Abstract 244: Increased Expression and Enhanced Vasorelaxation Activity of Specific Estrogen Receptor Subtypes in the Aorta and Mesenteric Vessels during Pregnancy

Pregnancy (Preg) is associated with hormonal and vascular changes, and estrogen (E2) may promote systemic vasodilation during Preg; however, the specific E2 receptor (ER), post-ER signaling mechanisms and vascular bed involved are unclear. To test if Preg is associated with distinct expression/activity of ERs in different blood vessels, BP and plasma E2 were measured in virgin and day-19 Preg rats, and the aorta, carotid, mesenteric and renal artery were isolated for measurement of ERα, ERβ and GPR30 expression, and the responses to E2 and specific ER agonists PPT (ERα), DPN (ERβ) and G1 (GPR30). BP was in Preg (89±6) < virgin (98±4mmHg), and plasma E2 was in Preg (120.5±5.8) > virgin (94.3±7.5pg/ml). Western blots revealed increased ERα and ERβ in aorta and mesenteric artery and GPR30 in aorta of Preg vs virgin. Immunohistochemistry revealed that the increases in ERs were mainly in intima and media. E2 and PPT caused greater relaxation of aorta of Preg (52.8±5.5, 49.3±11.4) than virgin (30.0±3.9, 19.3±3.8%) and of mesenteric artery of Preg (77.9±4.7, 75.4±4.5) than virgin (57.4±5.9, 46.5±9.5%), but similar relaxation in carotid and renal artery of Preg vs virgin. DPN and G1 caused greater relaxation in mesenteric and renal artery (15 to 30%) than aorta and carotid artery (<10%), but only aortic relaxation to G1 was in Preg (26.2±4.4) > virgin (5.3±6.7%). The NOS inhibitor L-NAME ± EDHF blocker tetraethylammonium or endothelium removal reduced PPT relaxation in aorta, suggesting an endothelium-dependent mechanism, but did not affect E2, PPT, DPN or G1-induced relaxation in other vessels, suggesting endothelium-independent mechanisms. PPT caused relaxation of Ca 2+ entry-dependent KCl contraction of mesenteric artery that was in Preg (69.7±5.5) > virgin rats (52.9±8.11%). Thus, during pregnancy, an increased ERα expression in endothelial and smooth muscle layers of aorta and mesenteric artery is associated with increased ERα-mediated relaxation via endothelium-derived vasodilators and direct inhibition of Ca 2+ entry pathways, supporting a role of aortic and mesenteric arterial ERα in pregnancy-associated systemic vasodilation. GPR30 may contribute to aortic dilation while the enhanced ERβ may mediate other genomic vascular effects during pregnancy.

Download Full-text

Adaptive increases in expression and vasodilator activity of estrogen receptor subtypes in a blood vessel-specific pattern during pregnancy

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00532.2015 ◽

2015 ◽

Vol 309 (10) ◽

pp. H1679-H1696 ◽

Cited By ~ 20

Author(s):

Karina M. Mata ◽

Wei Li ◽

Ossama M. Reslan ◽

Waleed T. Siddiqui ◽

Lauren A. Opsasnick ◽

...

Keyword(s):

Smooth Muscle ◽

Carotid Artery ◽

Blood Vessel ◽

Vascular Smooth Muscle ◽

Renal Artery ◽

G Protein ◽

Mesenteric Artery ◽

Receptor Subtypes ◽

Western Blots ◽

G Protein Coupled

Normal pregnancy is associated with adaptive hemodynamic, hormonal, and vascular changes, and estrogen (E2) may promote vasodilation during pregnancy; however, the specific E2 receptor (ER) subtype, post-ER signaling mechanism, and vascular bed involved are unclear. We tested whether pregnancy-associated vascular adaptations involve changes in the expression/distribution/activity of distinct ER subtypes in a blood vessel-specific manner. Blood pressure (BP) and plasma E2 were measured in virgin and pregnant ( day 19) rats, and the thoracic aorta, carotid artery, mesenteric artery, and renal artery were isolated for measurements of ERα, ERβ, and G protein-coupled receptor 30 [G protein-coupled ER (GPER)] expression and tissue distribution in parallel with relaxation responses to E2 (all ERs) and the specific ER agonist 4,4′,4″-(4-propyl-[1H]-pyrazole-1,3,5-triyl)-tris-phenol (PPT; ERα), diarylpropionitrile (DPN; ERβ), and G1 (GPER). BP was slightly lower and plasma E2 was higher in pregnant versus virgin rats. Western blots revealed increased ERα and ERβ in the aorta and mesenteric artery and GPER in the aorta of pregnant versus virgin rats. Immunohistochemistry revealed that the increases in ERs were mainly in the intima and media. In phenylephrine-precontracted vessels, E2 and PPT caused relaxation that was greater in the aorta and mesenteric artery but similar in the carotid and renal artery of pregnant versus virgin rats. DPN- and G1-induced relaxation was greater in the mesenteric and renal artery than in the aorta and carotid artery, and aortic relaxation to G1 was greater in pregnant versus virgin rats. The nitric oxide synthase inhibitor Nω-nitro-l-arginine methyl ester with or without the cyclooxygenase inhibitor indomethacin with or without the EDHF blocker tetraethylammonium or endothelium removal reduced E2, PPT, and G1-induced relaxation in the aorta of pregnant rats, suggesting an endothelium-dependent mechanism, but did not affect E2-, PPT-, DPN-, or G1-induced relaxation in other vessels, suggesting endothelium-independent mechanisms. E2, PPT, DPN, and G1 caused relaxation of Ca2+ entry-dependent KCl contraction, and the effect of PPT was greater in the mesenteric artery of pregnant versus virgin rats. Thus, during pregnancy, an increase in ERα expression in endothelial and vascular smooth muscle layers of the aorta and mesenteric artery is associated with increased ERα-mediated relaxation via endothelium-derived vasodilators and inhibition of Ca2+ entry into vascular smooth muscle, supporting a role of aortic and mesenteric arterial ERα in pregnancy-associated vasodilation. GPER may contribute to aortic relaxation while enhanced ERβ expression could mediate other genomic vascular effects during pregnancy.

Download Full-text

Role of EP2 and EP3 PGE2receptors in control of murine renal hemodynamics

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.2001.280.1.h327 ◽

2001 ◽

Vol 280 (1) ◽

pp. H327-H333 ◽

Cited By ~ 37

Author(s):

Laurent P. Audoly ◽

Xiaoping Ruan ◽

Victoria A. Wagner ◽

Jennifer L. Goulet ◽

Stephen L. Tilley ◽

...

Keyword(s):

Renal Artery ◽

Vascular Reactivity ◽

Renal Hemodynamics ◽

Receptor Subtypes ◽

Male Mice ◽

Unique Role ◽

Arterial Blood ◽

Renal Vascular

The kidney plays a central role in long-term regulation of arterial blood pressure and salt and water homeostasis. This is achieved in part by the local actions of paracrine and autacoid mediators such as the arachidonic acid-prostanoid system. The present study tested the role of specific PGE2 E-prostanoid (EP) receptors in the regulation of renal hemodynamics and vascular reactivity to PGE2. Specifically, we determined the extent to which the EP2 and EP3 receptor subtypes mediate the actions of PGE2 on renal vascular tone. Renal blood flow (RBF) was measured by ultrasonic flowmetry, whereas vasoactive agents were injected directly into the renal artery of male mice. Studies were performed on two independent mouse lines lacking either EP2or EP3 (−/−) receptors and the results were compared with wild-type controls (+/+). Our results do not support a unique role of the EP2 receptor in regulating overall renal hemodynamics. Baseline renal hemodynamics in EP2−/− mice [RBF EP2−/−: 5.3 ± 0.8 ml · min−1 · 100 g kidney wt−1; renal vascular resistance (RVR) 19.7 ± 3.6 mmHg · ml−1 · min · g kidney wt] did not differ statistically from control mice (RBF +/+: 4.0 ± 0.5 ml · min−1 · 100 g kidney wt−1; RVR +/+: 25.4 ± 4.9 mmHg · ml−1 · min · 100 g kidney wt−1). This was also the case for the peak RBF increase after local PGE2 (500 ng) injection into the renal artery (EP2−/−: 116 ± 4 vs. +/+: 112 ± 2% baseline RBF). In contrast, we found that the absence of EP3receptors in EP3−/− mice caused a significant increase (43%) in basal RBF (7.9 ± 0.8 ml · min−1 · g kidney wt−1, P < 0.05 vs. +/+) and a significant decrease (41%) in resting RVR (11.6 ± 1.4 mmHg · ml−1 · min · g kidney wt−1, P < 0.05 vs. +/+). Local administration of 500 ng of PGE2 into the renal artery caused more pronounced renal vasodilation in EP3−/− mice (128 ± 2% of basal RBF, P < 0.05 vs. +/+). We conclude that EP3 receptors mediate vasoconstriction in the kidney of male mice and its actions are tonically active in the basal state. Furthermore, EP3receptors are capable of buffering PGE2-mediated renal vasodilation.

Download Full-text

Evidence for the existence of endothelin-B receptor subtypes and their physiological roles in the rat

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1996.271.1.r254 ◽

1996 ◽

Vol 271 (1) ◽

pp. R254-R261 ◽

Cited By ~ 11

Author(s):

M. Gellai ◽

T. Fletcher ◽

M. Pullen ◽

P. Nambi

Keyword(s):

Radioligand Binding ◽

Rat Kidney ◽

Receptor Subtypes ◽

Sprague Dawley ◽

Vascular Effects ◽

Renal Vasoconstriction ◽

Eta Receptor ◽

Etb Receptor ◽

Endothelin B

The physiological roles of endothelin-B (ETB) receptor subtypes in systemic and renal hemodynamics were assessed in conscious Sprague-Dawley rats. Mean arterial pressure, hindlimb flow, and renal blood flow were measured via an implanted catheter and pulsed Doppler flow probes. Bolus intravenous injections of sarafotoxin 6c (S6c), a selective ETB agonist, elicited transient dose-dependent vasodilation, followed by sustained vasoconstriction in the systemic bed, but only vasoconstriction in the renal bed. RES-701-1, a selective ETB antagonist, blocked the dilator and potentiated the constrictor effect; SB-209670, a mixed ET receptor antagonist, attenuated both responses to S6c. In follow-up studies, the role of endogenous ET was assessed by administration of the antagonists alone: RES-701-1, SB-209670, and the ETA-selective antagonist BQ-123. RES-701-1 unmasked a significant systemic and renal vasoconstriction, which was attenuated by SB-209670 but not by BQ-123. SB-209670 and BQ-123 had no effect on basal hemodynamic parameters. Data from radioligand binding experiments showed that RES-701-1 binds with high affinity to the cloned human ETB receptor but poorly to the ETB receptor predominant in the rat kidney. Collectively, the results indicate that 1) the vascular effects of ET in the rat are mediated by two ETB receptor subtypes: an RES-701-1-sensitive subtype, mediating vasodilation, and an RES-701-1-insensitive subtype, mediating vasoconstriction; 2) the predominant role of endogenous ET is vasodilation; and 3) the ETA receptor plays a negligible role in the control of vascular tone in the rat.

Download Full-text

Role of muscular eNOS in skeletal arteries: Endothelium-independent hypoxic vasoconstriction of the femoral artery is impaired in eNOS-deficient mice

AJP Cell Physiology ◽

10.1152/ajpcell.00061.2016 ◽

2016 ◽

Vol 311 (3) ◽

pp. C508-C517 ◽

Cited By ~ 1

Author(s):

Hae Jin Kim ◽

Hae Young Yoo ◽

Hai Yue Lin ◽

Goo Taeg Oh ◽

Yin Hua Zhang ◽

...

Keyword(s):

Underlying Mechanism ◽

The Novel ◽

Nadph Oxidase 4 ◽

Hypoxic Vasoconstriction ◽

Nos Inhibitor ◽

Oxide Synthase ◽

Endothelial Nitric Oxide ◽

Dependent Mechanism ◽

Made In

We previously reported that hypoxia augments α-adrenergic contraction (hypoxic vasoconstriction, HVC) of skeletal arteries in rats. The underlying mechanism may involve hypoxic inhibition of endothelial nitric oxide synthase (eNOS) expressed in skeletal arterial myocytes (16). To further explore the novel role of muscular eNOS in the skeletal artery, we compared HVC in femoral arteries (FAs) from eNOS knockout (KO) mice with that from wild-type (WT) and heterozygous (HZ) mice. Immunohistochemical assays revealed that, in addition to endothelia, eNOS is also expressed in the medial layer of FAs, albeit at a much lower level. However, the medial eNOS signal was not evident in HZ FAs, despite strong expression in the endothelium; similar observations were made in WT carotid arteries (CAs). The amplitude of contraction induced by 1 μM phenylephrine (PhE) was greater in HZ than in WT FAs. Hypoxia (3% Po2) significantly augmented PhE-induced contraction in WT FAs but not in HZ or KO FAs. No HVC was observed in PhE-pretreated WT CAs. The NOS inhibitor nitro-l-arginine methyl ester (0.1 mM) also augmented PhE contraction in endothelium-denuded WT FAs but not in WT CAs. Inhibitors specific to neuronal NOS and inducible NOS did not augment PhE-induced contraction of WT FAs. NADPH oxidase 4 (NOX4) inhibitor (GKT137831, 5 μM), but not NOX2 inhibitor (apocynin, 100 μM), suppressed HVC. Consistent with the role of reactive oxygen species (ROS), HVC was also inhibited by pretreatment with tiron or polyethylene glycol-catalase. Taken together, these data suggest that the eNOS expressed in smooth muscle cells in FAs attenuates α-adrenergic vasoconstriction; this suppression is alleviated under hypoxia, which potentiates vasoconstriction in a NOX4/ROS-dependent mechanism.

Download Full-text

Differential effects of l-NAME on rat venular hydraulic conductivity

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.2000.279.4.h2017 ◽

2000 ◽

Vol 279 (4) ◽

pp. H2017-H2023 ◽

Cited By ~ 32

Author(s):

Rolando E. Rumbaut ◽

Jianjie Wang ◽

Virginia H. Huxley

Keyword(s):

Nitric Oxide ◽

Blood Flow ◽

Methyl Ester ◽

Hydraulic Conductivity ◽

No Synthase ◽

Vascular Effects ◽

Nos Inhibitors ◽

Before And After ◽

Nos Inhibitor

The role of nitric oxide (NO) in microvascular permeability remains unclear because both increases and decreases in permeability by NO synthase (NOS) inhibitors have been reported. We sought to determine whether blood-borne constituents modify venular permeability responses to the NOS inhibitor N G-nitro-l-arginine methyl ester (l-NAME). We assessed hydraulic conductivity ( L p) of pipette-perfused rat mesenteric venules before and after exposure to 10−4 M l-NAME. In the absence of blood-borne constituents, l-NAME reduced L p by nearly 50% (from a median of 2.4 × 10−7cm · s−1 · cmH2O−1, n = 17, P < 0.001). The reduction in L p by l-NAME was inhibited by a 10-fold molar excess of l-arginine but notd-arginine ( n = 6). In a separate group of venules, blood flow was allowed to resume during exposure tol-NAME. In vessels perfused by blood duringl-NAME exposure, L p increased by 78% (from 1.4 × 10−7cm · s−1 · cmH2O−1, n = 10, P < 0.01). N G-nitro-d-arginine methyl ester did not affect L p in either of the two groups. These data imply that NO has direct vascular effects on permeability that are opposed by secondary changes in permeability mediated by blood-borne constituents.

Download Full-text