scholarly journals Ryanodine receptor subtypes regulate Ca2+ sparks/spontaneous transient outward currents and myogenic tone of uterine arteries in pregnancy

2020 ◽  
Author(s):  
Rui Song ◽  
Xiang-Qun Hu ◽  
Monica Romero ◽  
Mark A Holguin ◽  
Whitney Kagabo ◽  
...  
Keyword(s):  
Ryanodine Receptor ◽  
Uterine Artery ◽  
Vascular Tone ◽  
Myogenic Tone ◽  
Receptor Subtypes ◽  
Α Subunit ◽  
Uterine Arteries ◽  
Outward Currents ◽  
Pregnant Sheep ◽  
Spontaneous Transient Outward Currents

Abstract Aims Our recent study demonstrated that increased Ca2+ sparks and spontaneous transient outward currents (STOCs) played an important role in uterine vascular tone and haemodynamic adaptation to pregnancy. The present study examined the role of ryanodine receptor (RyR) subtypes in regulating Ca2+ sparks/STOCs and myogenic tone in uterine arterial adaptation to pregnancy. Methods and results Uterine arteries isolated from non-pregnant and near-term pregnant sheep were used in the present study. Pregnancy increased the association of α and β1 subunits of large-conductance Ca2+-activated K+ (BKCa) channels and enhanced the co-localization of RyR1 and RyR2 with the β1 subunit in the uterine artery. In contrast, RyR3 was not co-localized with BKCa β1 subunit. Knockdown of RyR1 or RyR2 in uterine arteries of pregnant sheep downregulated the β1 but not α subunit of the BKCa channel and decreased the association of α and β1 subunits. Unlike RyR1 and RyR2, knockdown of RyR3 had no significant effect on either expression or association of BKCa subunits. In addition, knockdown of RyR1 or RyR2 significantly decreased Ca2+ spark frequency, suppressed STOCs frequency and amplitude, and increased pressure-dependent myogenic tone in uterine arteries of pregnant animals. RyR3 knockdown did not affect Ca2+ sparks/STOCs and myogenic tone in the uterine artery. Conclusion Together, the present study demonstrates a novel mechanistic paradigm of RyR subtypes in the regulation of Ca2+ sparks/STOCs and uterine vascular tone, providing new insights into the mechanisms underlying uterine vascular adaptation to pregnancy.

scholarly journals Pregnancy attenuates uterine artery pressure-dependent vascular tone: role of PKC/ERK pathway

2006 ◽  
Vol 290 (6) ◽  
pp. H2337-H2343 ◽  
Author(s):  
DaLiao Xiao ◽  
John N. Buchholz ◽  
Lubo Zhang
Keyword(s):  
Uterine Artery ◽  
Vascular Tone ◽  
Mek Inhibitor ◽  
Intraluminal Pressure ◽  
Myogenic Tone ◽  
Uterine Arteries ◽  
Intracellular Ca ◽  
Myogenic Responses ◽  
The Difference ◽  
Near Term

The mechanisms of adaptation of uterine artery vascular tone to pregnancy are not fully understood. The present study tested the hypothesis that pregnancy decreases the PKC-mediated Ca2+ sensitivity of the contractile process and attenuates myogenic tone in resistance-sized uterine arteries. In pressurized uterine arteries from nonpregnant (NPUA) and near-term pregnant (PUA) sheep, we measured, simultaneously in the same tissue, vascular diameter and vessel wall intracellular Ca2+ concentration ([Ca2+]i) as a function of intraluminal pressure. In both NPUA and PUA, membrane depolarization with KCl caused a rapid increase in [Ca2+]i and a decrease in diameter. A pressure increase from 20 to 100 mmHg resulted in a transient increase in diameter that was associated with an increase in [Ca2+]i, followed by myogenic contractions in the absence of further changes in [Ca2+]i. In addition, activation of PKC by phorbol 12,13-dibutyrate induced a decrease in diameter in the absence of changes in [Ca2+]i. Pressure-dependent myogenic responses were significantly decreased in PUA compared with NPUA. However, pressure-induced increases in [Ca2+]i were not significantly different between PUA and NPUA. The ratio of changes in diameter to changes in [Ca2+]i was significantly greater for pressure-induced contraction of NPUA than that of PUA. Inhibition of PKC by calphostin C significantly attenuated the pressure-induced vascular tone and eliminated the difference of myogenic responses between NPUA and PUA. In contrast, the MAPKK (MEK) inhibitor PD-098059 had no effect on NPUA but significantly enhanced myogenic responses of PUA. In the presence of PD-098059, there was no difference in pressure-induced myogenic responses between NPUA and PUA. The results suggest that pregnancy downregulates pressure-dependent myogenic tone of the uterine artery, which is partly due to increased MEK/ERK activity and decreased PKC signal pathway leading to a decrease in Ca2+ sensitivity of myogenic mechanism in the uterine artery during pregnancy.

scholarly journals Gestational Hypoxia Inhibits Pregnancy-Induced Upregulation of Ca 2+ Sparks and Spontaneous Transient Outward Currents in Uterine Arteries Via Heightened Endoplasmic Reticulum/Oxidative Stress

Hypertension ◽  
2020 ◽  
Vol 76 (3) ◽  
pp. 930-942
Author(s):  
Xiang-Qun Hu ◽  
Rui Song ◽  
Monica Romero ◽  
Chiranjib Dasgupta ◽  
Joseph Min ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Endoplasmic Reticulum ◽  
High Altitude ◽  
Pregnancy Complications ◽  
Myogenic Tone ◽  
Vascular Adaptation ◽  
Uterine Arteries ◽  
Outward Currents ◽  
Low Altitude ◽  
Spontaneous Transient Outward Currents

Hypoxia during pregnancy profoundly affects uterine vascular adaptation and increases the risk of pregnancy complications, including preeclampsia and fetal intrauterine growth restriction. We recently demonstrated that increases in Ca 2+ sparks and spontaneous transient outward currents (STOCs) played an essential role in pregnancy-induced uterine vascular adaptation. In the present study, we hypothesize that gestational hypoxia suppresses Ca 2+ sparks/STOCs coupling leading to increased uterine vascular tone via enhanced endoplasmic reticulum (ER)/oxidative stress. Uterine arteries were obtained from nonpregnant and near-term pregnant sheep residing in low altitude or acclimatizing to high-altitude (3801 m) hypoxia for ≈110 days. High-altitude hypoxia suppressed pregnancy-induced upregulation of RyR1 and RyR2 (ryanodine receptor 1 and 2) protein abundance, Ca 2+ sparks, and STOCs in uterine arteries. Inhibition of Ca 2+ sparks/STOCs with the RyR inhibitor ryanodine significantly increased pressure-dependent myogenic tone in uterine arteries from low-altitude normoxic pregnant animals but not those from high-altitude hypoxic pregnant animals. Gestational hypoxia significantly increased ER/oxidative stress in uterine arteries. Of importance, the hypoxia-mediated suppression of Ca 2+ sparks/STOCs and increase in myogenic tone in uterine arteries of pregnant animals were reversed by inhibiting ER/oxidative stress. Of great interest, the impaired sex hormonal regulation of STOCs in high-altitude animals was annulled by scavenging reactive oxygen species but not by inhibiting ER stress. Together, the findings reveal the differential mechanisms of ER and oxidative stresses in suppressing Ca 2+ sparks/STOCs and increasing myogenic tone of uterine arteries in hypoxia during gestation, providing new insights into the understanding of pregnancy complications associated with hypoxia.

scholarly journals Local Over-Expression of VEGF-DΔNΔC in the Uterine Arteries of Pregnant Sheep Results in Long-Term Changes in Uterine Artery Contractility and Angiogenesis

PLoS ONE ◽  
2014 ◽  
Vol 9 (6) ◽  
pp. e100021 ◽  
Author(s):  
Vedanta Mehta ◽  
Khalil N. Abi-Nader ◽  
Panicos Shangaris ◽  
S. W. Steven Shaw ◽  
Elisa Filippi ◽  
...  
Keyword(s):  
Uterine Artery ◽  
Over Expression ◽  
Uterine Arteries ◽  
Pregnant Sheep ◽  
Long Term Changes

Adaptation of uterine artery thick- and thin-filament regulatory pathways to pregnancy

2005 ◽  
Vol 288 (1) ◽  
pp. H142-H148 ◽  
Author(s):  
DaLiao Xiao ◽  
Lubo Zhang
Keyword(s):  
Uterine Artery ◽  
Thin Filament ◽  
Kinase Inhibitor ◽  
Isometric Tension ◽  
Mitogen Activated Protein Kinase ◽  
Regulatory Pathways ◽  
Uterine Arteries ◽  
Pregnant Sheep ◽  
Mitogen Activated Protein ◽  
Near Term

Little is known about the adaptation of uterine artery smooth muscle contractile mechanisms to pregnancy. The present study tested the hypothesis that pregnancy differentially regulates thick- and thin-filament regulatory pathways in uterine arteries. Isometric tension, intracellular free Ca2+ concentration, and phosphorylation of 20-kDa myosin light chain (MLC20) were measured simultaneously in uterine arteries isolated from nonpregnant and near-term (140 days gestation) pregnant sheep. Phenylephrine-mediated intracellular free Ca2+ concentration, MLC20 phosphorylation, and contraction tension were significantly increased in uterine arteries of pregnant compared with nonpregnant animals. In contrast, phenylephrine-mediated Ca2+ sensitivity of MLC20 phosphorylation was decreased in the uterine arteries of pregnant sheep. Simultaneous measurement of phenylephrine-stimulated tension and MLC20 phosphorylation in the same tissue indicated a decrease in MLC20 phosphorylation-independent contractions in the uterine arteries of pregnant sheep. In addition, activation of PKC produced significantly lower sustained contractions in uterine arteries of pregnant compared with nonpregnant animals in the absence of changes in MLC20 phosphorylation levels in either vessels. In uterine arteries of nonpregnant sheep, the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase inhibitor PD-098059 significantly increased phenylephrine-mediated, MLC20 phosphorylation-independent contractions. The results suggest that in uterine arteries, pregnancy upregulates α1-adrenoceptor-mediated Ca2+ mobilization and MLC20 phosphorylation. In contrast, pregnancy downregulates the Ca2+ sensitivity of myofilaments, which is mediated by both thick- and thin-filament pathways.

Estrogen regulates β1-subunit expression in Ca2+-activated K+ channels in arteries from reproductive tissues

2005 ◽  
Vol 289 (4) ◽  
pp. H1417-H1427 ◽  
Author(s):  
Deepa Nagar ◽  
Xiao-tie Liu ◽  
Charles R. Rosenfeld
Keyword(s):  
Vascular Tone ◽  
Immunoblot Analysis ◽  
Uterine Blood Flow ◽  
Α Subunit ◽  
Uterine Arteries ◽  
Subunit Mrna ◽  
Reverse Transcription Pcr ◽  
Subunit Expression ◽  
Estradiol 17Β ◽  
Α Subunits

Daily estradiol-17β (E2β) increases basal uterine blood flow (UBF) and enhances acute E2β-mediated increases in UBF in ovariectomized nonpregnant ewes. The acute E2β-mediated rise in UBF involves vascular smooth muscle (VSM) large-conductance Ca2+-activated K+ channels (BKCa). BKCa consist of pore-forming α-subunits and regulatory β1-subunits that modulate channel function and E2β responsiveness. It is unclear whether E2β also alters subunit expression and thus channel density and/or function, thereby contributing to the rise in basal UBF and enhanced UBF responses that follow daily E2β. Therefore, we examined BKCa subunit expression by using reverse transcription-PCR and immunoblot analysis of arterial VSM from reproductive and nonreproductive tissues and myometrium from ovariectomized nonpregnant ewes after daily E2β (1 μg/kg iv) or vehicle without or with acute E2β (1 μg/kg). Tissue distribution was determined by immunohistochemistry. Acute E2β did not alter α- or β1-subunit expression in any tissue ( P > 0.1). Daily E2β also did not affect α-subunit mRNA or protein in any tissue ( P > 0.1) or mesenteric arterial VSM β1-subunit. However, daily E2β increased uterine and mammary arterial VSM β1-subunit mRNA by 32% and 83% ( P < 0.05), uterine VSM protein by 30%, and myometrial β1-subunit mRNA and protein by 74% ( P ≤ 0.005). Immunostaining of uterine arteries, myometrium, and intramyometrial arteries paralleled immunoblot analyses for both subunits. Although BKCa density is unaffected by daily and acute E2β, daily E2β increases β1-subunit in proximal and distal uterine arterial VSM. Thus prolonged E2β exposure may alter BKCa function, estrogen responsiveness, and basal vascular tone and reactivity in reproductive arteries by modifying α:β1 stoichiometry.

scholarly journals MicroRNA-210 Mediates Hypoxia-Induced Repression of Spontaneous Transient Outward Currents in Sheep Uterine Arteries During Gestation

Hypertension ◽  
2021 ◽  
Vol 77 (4) ◽  
pp. 1412-1427
Author(s):  
Xiang-Qun Hu ◽  
Chiranjib Dasgupta ◽  
Rui Song ◽  
Monica Romero ◽  
Sean M. Wilson ◽  
...  
Keyword(s):  
High Altitude ◽  
Intrauterine Growth Restriction ◽  
Hormonal Regulation ◽  
Outward Current ◽  
Transient Outward Current ◽  
Uterine Arteries ◽  
Outward Currents ◽  
Low Altitude ◽  
Spontaneous Transient Outward Currents

Hypoxia during pregnancy is a major contributor to the pathogenesis of preeclampsia and intrauterine growth restriction. Our recent studies revealed that pregnancy-induced uterine vascular adaptation depended on the enhanced Ca 2+ spark/spontaneous transient outward current (STOC) coupling and hypoxia during gestation diminished this adaption. In the present study, we test the hypothesis of a mechanistic link of microRNA-210 (miR-210) in hypoxia-impaired Ca 2+ spark/STOC coupling in uterine arteries. Pregnant ewes acclimatized to high-altitude (3801 m) hypoxia for ≈110 days significantly increased circulation levels of miR-210 in both the ewe and her fetus. Treatment of uterine arteries from high-altitude animals with the antagomir miR-210-LNA recovered hypoxia-repressed STOCs in pregnant ewes and restored the hormonal regulation of STOCs in nonpregnant animals. In uterine arteries from low-altitude control animals, miR-210 mimic suppressed STOCs in pregnant ewes and inhibited the hormonal regulation of STOCs in nonpregnant animals. Mechanistically, miR-210 directly targeted and downregulated type 2 ryanodine receptor and large-conductance Ca 2+ -activated K + channel β1 subunit, resulting in significant decreases in Ca 2+ sparks and STOCs in uterine arteries. In addition, miR-210 indirectly decreased STOCs by targeting ten-eleven translocation methylcytosine dioxygenase. Together, the present study revealed a mechanistic link of miR-210 in hypoxia-induced repression of Ca 2+ spark/STOC coupling in uterine arteries during gestation, providing novel insights into the understanding of pregnancy complications associated with hypoxia and the potential therapeutic targets.

Effects of chronic hypoxia on Ca2+ mobilization and Ca2+ sensitivity of myofilaments in uterine arteries

1998 ◽  
Vol 274 (1) ◽  
pp. H132-H138 ◽  
Author(s):  
Lubo Zhang ◽  
Daliao Xiao
Keyword(s):  
Smooth Muscle ◽  
Fluorescence Intensity ◽  
Uterine Artery ◽  
Chronic Hypoxia ◽  
Effective Concentration ◽  
Uterine Arteries ◽  
Agonist Stimulation ◽  
Pregnant Sheep ◽  
Half Maximal Effective Concentration ◽  
Intracellular Ca

The effect of chronic hypoxia on free intracellular Ca2+ concentration ([Ca2+]i) and Ca2+ sensitivity of myofilaments during agonist stimulation was examined in uterine arteries obtained from normoxic and chronically hypoxic pregnant sheep maintained at high altitude (3,820 m) for ∼110 days. Smooth muscle [Ca2+]iwas measured simultaneously with muscle contraction in the same intact tissue. Whereas both KCl and 5-HT increased [Ca2+]iand tension simultaneously in the uterine artery, 5-HT produced significantly greater contractile tension (in g) than KCl at a given amount of [Ca2+]ias indicated by the ratio of fura 2 fluorescence intensity induced by excitation at 340 nm to that induced at 380 nm (29.8 ± 6.9 vs. 16.9 ± 4.0, P < 0.05). Chronic hypoxia did not change KCl-induced contractions, nor did it affect KCl-mediated increases in [Ca2+]i. In contrast, chronic hypoxia significantly inhibited 5-HT-induced contractions and decreased the 5-HT-stimulated increase in [Ca2+]i(pD2 7.46 ± 0.18 → 6.86 ± 0.11, P < 0.05, where pD2 is −log half-maximal effective concentration) in uterine arteries. In addition, the slope (g tension/nM [Ca2+]i) of the 5-HT-mediated [Ca2+]i-tension relationship was significantly decreased in chronically hypoxic arteries (0.024 ± 0.002 → 0.013 ± 0.001, P < 0.01). The results suggest that chronic hypoxia suppresses agonist-mediated Ca2+ homeostasis in uterine arteries by inhibiting Ca2+mobilization and the agonist-enhanced Ca2+ sensitivity of myofilaments.

Upregulation of eNOS in pregnant ovine uterine arteries by chronic hypoxia

2001 ◽  
Vol 280 (2) ◽  
pp. H812-H820 ◽  
Author(s):  
Daliao Xiao ◽  
Ian M. Bird ◽  
Ronald R. Magness ◽  
Lawrence D. Longo ◽  
Lubo Zhang
Keyword(s):  
Uterine Artery ◽  
Chronic Hypoxia ◽  
Enos Gene ◽  
Ionophore A23187 ◽  
Mrna Levels ◽  
Uterine Arteries ◽  
Pregnant Sheep ◽  
No Release ◽  
Endothelium Dependent Relaxation ◽  
Enos Protein

We tested the hypothesis that chronic high-altitude (3,820 m) hypoxia during pregnancy was associated with the upregulation of endothelial nitric oxide (NO) synthase (eNOS) protein and mRNA in ovine uterine artery endothelium and enhanced endothelium-dependent relaxation. In pregnant sheep, norepinephrine-induced dose-dependent contractions were increased by removal of the endothelium in both control and hypoxic uterine arteries. The increment was significantly higher in hypoxic tissues. The calcium ionophore A23187 -induced relaxation of the uterine artery was significantly enhanced in hypoxic compared with control tissues. However, sodium nitroprusside- and 8-bromoguanosine 3′,5′-cyclic monophosphate-induced relaxations were not changed. Accordingly, chronic hypoxia significantly increased basal and A23187 -induced NO release. Chronic hypoxia increased eNOS protein and mRNA levels in the endothelium from uterine but not femoral or renal arteries. In nonpregnant animals, chronic hypoxia increased eNOS mRNA in uterine artery endothelium but had no effects on eNOS protein, NO release, or endothelium-dependent relaxation. Chronic hypoxia selectively augments pregnancy-associated upregulation of eNOS gene expression and endothelium-dependent relaxation of the uterine artery.

scholarly journals Chronic hypoxia increases pressure-dependent myogenic tone of the uterine artery in pregnant sheep: role of ERK/PKC pathway

2009 ◽  
Vol 296 (6) ◽  
pp. H1840-H1849 ◽  
Author(s):  
Katherine Chang ◽  
Daliao Xiao ◽  
Xiaohui Huang ◽  
Lawrence D. Longo ◽  
Lubo Zhang
Keyword(s):  
Uterine Artery ◽  
Chronic Hypoxia ◽  
Ex Vivo ◽  
Signal Pathway ◽  
Myogenic Tone ◽  
Uterine Blood Flow ◽  
Pregnant Sheep ◽  
Near Term ◽  
Do So

Chronic hypoxia during pregnancy has profound effects on uterine artery (UA) contractility and attenuates uterine blood flow. The present study tested the hypothesis that chronic hypoxia inhibits the pregnancy-induced reduction in pressure-dependent myogenic tone of resistance-sized UAs. UAs were isolated from nonpregnant ewes (NPUAs) and near-term pregnant ewes (PUAs) that had been maintained at sea level (∼300 m) or at high altitude (3,801 m) for 110 days. In normoxic animals, the pressure-dependent myogenic response was significantly attenuated in PUAs compared with NPUAs. Hypoxia significantly increased myogenic tone in PUAs and abolished its difference between PUAs and NPUAs. Consistently, there was a significant increase in PKC-mediated baseline Ca2+ sensitivity of PUAs in hypoxic animals. Hypoxia significantly increased phorbol 12,13-dibutyrate (PDBu)-induced contractions in PUAs but not in NPUAs. Whereas the inhibition of ERK1/2 by PD-98059 potentiated PDBu-mediated contractions of PUAs in normoxic animals, it failed to do so in hypoxic animals. Hypoxia decreased ERK1/2 expression in PUAs. PDBu induced membrane translocation of PKC-α and PKC-ε. Whereas there were no significant differences in PKC-α translocation among all groups, the translocation of PKC-ε was significantly enhanced in NPUAs compared with PUAs in normoxic animals, and hypoxia significantly increased PKC-ε translocation in PUAs. In the presence of PD-98059, there were no significant differences in PDBu-induced PKC-ε translocation among all groups. Treatment of PUAs isolated from normoxic animals with 10.5% O2 for 48 h ex vivo significantly increased PDBu-induced contractions and eliminated its difference between PUAs and NPUAs. The results suggest that hypoxia upregulates pressure-dependent myogenic tone through its direct effect in suppressing ERK1/2 activity and increasing the PKC signal pathway, leading to an increase in the Ca2+ sensitivity of the myogenic mechanism in the UA during pregnancy.

ERK MAP kinases regulate smooth muscle contraction in ovine uterine artery: effect of pregnancy

2002 ◽  
Vol 282 (1) ◽  
pp. H292-H300 ◽  
Author(s):  
Daliao Xiao ◽  
Lubo Zhang
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Uterine Artery ◽  
Map Kinases ◽  
Smooth Muscle Contraction ◽  
Isometric Tension ◽  
Uterine Arteries ◽  
Kinase C ◽  
Pregnant Sheep

The present study investigated the potential role of extracellular signal-regulated kinase (ERK) in uterine artery contraction and tested the hypothesis that pregnancy upregulated ERK-mediated function in the uterine artery. Isometric tension in response to phenylephrine (PE), serotonin (5-HT), phorbol 12,13-dibutyrate (PDBu), and KCl was measured in the ring preparation of uterine arteries obtained from nonpregnant and near-term (140 days gestation) pregnant sheep. Inhibiting ERK activation with PD-98059 did not change the KCl-evoked contraction but significantly inhibited the contraction to 5-HT in both nonpregnant and pregnant uterine arteries. PD-98059 did not affect PE-induced contraction in the uterine arteries of nonpregnant sheep but significantly decreased it in the uterine arteries of pregnant sheep. In accordance, PE stimulated activation of ERK in uterine arteries of pregnant sheep, which was blocked by PD-98059. PD-98059-mediated inhibition of the PE-induced contraction was associated with a decrease in both intracellular Ca2+ concentration and Ca2+ sensitivity of contractile proteins in the uterine arteries of pregnant sheep. PDBu-mediated contraction was significantly less in pregnant than in nonpregnant uterine arteries. PD-98059 had no effect on PDBu-induced contraction in nonpregnant but significantly increased it in pregnant uterine arteries. In addition, PD-98059 significantly enhanced PDBu-stimulated protein kinase C activity. The results indicate that ERK plays an important role in the regulation of uterine artery contractility, and its effect is agonist dependent. More importantly, pregnancy selectively enhances the role of ERK in α1-adrenoceptor-mediated contractions and its effect in suppressing protein kinase C-mediated contraction in the uterine artery.

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