Heightened Vascular Reactivity Following Sympathetic Denervation Correlates with Increased Expression of C-Kit and Connexin43

Hypertension ◽  
2000 ◽  
Vol 36 (suppl_1) ◽  
pp. 706-706
Author(s):  
David Paul Slovut ◽  
Anne N Dorrance ◽  
Frank C Brosius ◽  
Stephanie W Watts ◽  
R. Clinton Webb
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Vascular Reactivity ◽  
Contractile Activity ◽  
Sympathetic Denervation ◽  
Oscillatory Activity ◽  
Maximal Response ◽  
Mrna Levels ◽  
Pacemaker Cells ◽  
Cx43 Expression

P71 Short-term denervation produces supersensitivity to α-adrenergic agonists that resembles the heightened vascular reactivity observed in hypertensive subjects. Gap junctions, transmembrane channels responsible for cell-to-cell communication, may play a role in maintaining increased vascular reactivity. We examined the effects of denervation with intra-peritoneal reserpine 3 mg/kg/day (N=5) or topical 5% phenol-glycerol (N=7) on agonist-induced oscillatory activity. Wistar-Kyoto (WKY) rat tail arteries were exposed to step-wise addition of norepinephrine (NE) 10 -9 M-10 -5 M. The concentration for half-maximal response for NE-induced contraction was lower in reserpine- and phenol-treated vessels than controls (log EC 50 [mol]/L control -6.89 vs reserpine -7.16, p<0.05); control -6.86 vs phenol -7.32, p<0.0001). Incubation in K + -free solution produced an 8-fold increase in isometric tension in control vs denervated vessels (138.4±23.2 vs 17.2±4.5 % of contraction to phenylephrine 10 -6 M, p<0.001). These findings are consistent with adrenergic denervation. Agonist-induced oscillatory activity was observed in 5/5 reserpine- and 4/7 phenol-treated vessels vs 0/12 controls (Fischer’s exact test p<0.05). The highly selective gap junction inhibitor, Gap27 (10 mM), nearly abolished NE-induced vascular smooth muscle oscillations. Reverse transcriptase polymerase chain reaction was carried out for connexin43 (Cx43) and c-Kit, a marker for non-neural interstitial cells that serve as pacemaker cells, using specific oligonucleotide primers. Following denervation, mRNA levels of Cx43 remained unchanged while levels of c-Kit increased markedly (0.16±0.03 vs 0.62±0.13 a.u., p<0.05). Western blot analysis revealed near doubling of Cx43 protein after denervation (80.0±13.7 vs 41.4±5.7 a.u., p<0.05). In conclusion, sympathetic denervation produced increased agonist-induced oscillatory contractile activity in vascular smooth muscle. The heightened vascular reactivity may result from upregulation of pacemaker cells and increased Cx43 expression.

Mechanisms of Hydrogen Sulfide Effects on Contractile Activity of Vascular Smooth Muscle in Rats

2012 ◽  
Vol 3 (2) ◽  
pp. 149-160
Author(s):  
Olena M. Semenykhina ◽  
Olga V. Bazilyuk ◽  
Yulia P. Korkach ◽  
Vadim F. Sagach
Keyword(s):  
Smooth Muscle ◽  
Hydrogen Sulfide ◽  
Vascular Smooth Muscle ◽  
Contractile Activity

Mechanisms of Direct Inhibitory Action of Isoflurane on Vascular Smooth Muscle of Mesenteric Resistance Arteries

2003 ◽  
Vol 99 (3) ◽  
pp. 666-677 ◽  
Author(s):  
Takashi Akata ◽  
Tomoo Kanna ◽  
Jun Yoshino ◽  
Shosuke Takahashi
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Vascular Reactivity ◽  
Channel Blocker ◽  
Isometric Force ◽  
Systemic Resistance ◽  
Resistance Arteries ◽  
Voltage Gated ◽  
Fura 2 ◽  
Force Relation

Background Isoflurane has been shown to directly inhibit vascular reactivity. However, less information is available regarding its underlying mechanisms in systemic resistance arteries. Methods Endothelium-denuded smooth muscle strips were prepared from rat mesenteric resistance arteries. Isometric force and intracellular Ca2+ concentration ([Ca2+]i) were measured simultaneously in the fura-2-loaded strips, whereas only the force was measured in the beta-escin membrane-permeabilized strips. Results Isoflurane (3-5%) inhibited the increases in both [Ca2+]i and force induced by either norepinephrine (0.5 microM) or KCl (40 mM). These inhibitions were similarly observed after depletion of intracellular Ca2+ stores by ryanodine. Regardless of the presence of ryanodine, after washout of isoflurane, its inhibition of the norepinephrine response (both [Ca2+]i and force) was significantly prolonged, whereas that of the KCl response was quickly restored. In the ryanodine-treated strips, the norepinephrine- and KCl-induced increases in [Ca2+]i were both eliminated by nifedipine, a voltage-gated Ca2+ channel blocker, whereas only the former was inhibited by niflumic acid, a Ca2+-activated Cl- channel blocker. Isoflurane caused a rightward shift of the Ca2+-force relation only in the fura-2-loaded strips but not in the beta-escin-permeabilized strips. Conclusions In mesenteric resistance arteries, isoflurane depresses vascular smooth muscle reactivity by directly inhibiting both Ca2+ mobilization and myofilament Ca2+ sensitivity. Isoflurane inhibits both norepinephrine- and KCl-induced voltage-gated Ca2+ influx. During stimulation with norepinephrine, isoflurane may prevent activation of Ca2+-activated Cl- channels and thereby inhibit voltage-gated Ca2+ influx in a prolonged manner. The presence of the plasma membrane appears essential for its inhibition of the myofilament Ca2+ sensitivity.

Effect of SR-49059, a vasopressin V1a antagonist, on human vascular smooth muscle cells

1995 ◽  
Vol 268 (1) ◽  
pp. H404-H410 ◽  
Author(s):  
C. Serradeil-Le Gal ◽  
J. M. Herbert ◽  
C. Delisee ◽  
P. Schaeffer ◽  
D. Raufaste ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Specific Binding ◽  
Muscle Cells ◽  
Maximal Response ◽  
Receptor Subtypes ◽  
Functional Studies ◽  
Antagonist Binding

The effects of SR-49059, a new nonpeptide and selective arginine vasopressin (AVP) V1a antagonist, were investigated in binding and functional studies on cultured human aortic vascular smooth muscle cells (VSMC). Characterization of human vascular V1a receptors, using a specific V1a radioiodinated ligand, showed that [125I]-linear AVP antagonist binding to human VSMC membranes was time dependent, reversible, and saturable. A single population of high-affinity binding sites (apparent equilibrium dissociation constant = 15 +/- 6 pM; maximum binding density = 36 +/- 5 fmol/mg protein, i.e., approximately 3,000 sites/cell) with the expected V1a profile was identified. Exposure of these cells to AVP dose-dependently produced cytosolic free [Ca2+] increase [AVP concentration required to obtain a half-maximal response (EC50) = 23 +/- 9 nM] and proliferation (EC50 = 3.2 +/- 0.5 nM). SR-49059 strongly and stereospecifically inhibited [125I]-linear AVP antagonist binding to VSMC V1a receptors [inhibition constant (Ki) = 1.4 +/- 0.3 nM], AVP-evoked Ca2+ increase [concentration of inhibitor required to obtain 50% inhibition of specific binding (IC50) = 0.41 +/- 0.06 nM], and the mitogenic effects induced by 100 nM AVP (IC50 = 0.83 +/- 0.04 nM). OPC-21268, another nonpeptide V1a antagonist, was more than two orders of magnitude less potent than SR-49059 in these models. However, the consistent affinity (Ki = 138 +/- 21 nM) and activity found with OPC-21268 on human VSMC in comparison with the inactivity already observed for other human V1a receptors (liver, platelets, adrenals, and uterus) strongly suggested the existence of human AVP V1a-receptor subtypes.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Fundamental Roles of Axial Stretch in Isometric and Isobaric Evaluations of Vascular Contractility

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Alexander W. Caulk ◽  
Jay D. Humphrey ◽  
Sae-Il Murtada
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Muscle Function ◽  
Contractile Function ◽  
Contractile Activity ◽  
Comparison Of Methods ◽  
Axial Stretch ◽  
Smooth Muscle Function ◽  
In Vivo Loading

Vascular smooth muscle cells (VSMCs) can regulate arterial mechanics via contractile activity in response to changing mechanical and chemical signals. Contractility is traditionally evaluated via uniaxial isometric testing of isolated rings despite the in vivo environment being very different. Most blood vessels maintain a locally preferred value of in vivo axial stretch while subjected to changes in distending pressure, but both of these phenomena are obscured in uniaxial isometric testing. Few studies have rigorously analyzed the role of in vivo loading conditions in smooth muscle function. Thus, we evaluated effects of uniaxial versus biaxial deformations on smooth muscle contractility by stimulating two regions of the mouse aorta with different vasoconstrictors using one of three testing protocols: (i) uniaxial isometric testing, (ii) biaxial isometric testing, and (iii) axially isometric plus isobaric testing. Comparison of methods (i) and (ii) revealed increased sensitivity and contractile capacity to potassium chloride and phenylephrine (PE) with biaxial isometric testing, and comparison of methods (ii) and (iii) revealed a further increase in contractile capacity with isometric plus isobaric testing. Importantly, regional differences in estimated in vivo axial stretch suggest locally distinct optimal biaxial configurations for achieving maximal smooth muscle contraction, which can only be revealed with biaxial testing. Such differences highlight the importance of considering in vivo loading and geometric configurations when evaluating smooth muscle function. Given the physiologic relevance of axial extension and luminal pressurization, we submit that, when possible, axially isometric plus isobaric testing should be employed to evaluate vascular smooth muscle contractile function.

Binding, degradation, and biological activity of insulin in vascular smooth muscle cells

1985 ◽  
Vol 249 (3) ◽  
pp. E292-E298
Author(s):  
N. Kaiser ◽  
A. Tur-Sinai ◽  
M. Hasin ◽  
E. Cerasi
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Cultured Cells ◽  
Muscle Cells ◽  
Insulin Binding ◽  
Maximal Response ◽  
Maximal Effect ◽  
Dependent Manner ◽  
Igf I

The interaction of insulin with the vascular smooth muscle was studied using cultures derived from the bovine aortic arch. The cultured cells exhibited specific binding of 125I-insulin that was reversible and dependent on pH. Both insulin and insulinlike growth factor (IGF) I competed for 125I-insulin binding; IGF I, however, was less effective than insulin by at least an order of magnitude. Insulin binding was accompanied by internalization and degradation of the hormone in a temperature- and time-dependent manner. Chloroquine and other lysosomotropic agents elevated the internalized insulin and reduced its degradation. Pre-exposure of cell cultures to insulin resulted in downregulation of cell surface receptors. Insulin stimulated alpha-aminoisobutyric acid transport in confluent smooth muscle cells. The maximal response was observed at 100 ng/ml insulin with a half-maximal effect at 10 ng/ml. Sparse, serum-starved smooth muscle cells responded to insulin with a dose-dependent increase in [3H]-thymidine incorporation into DNA. Although the effect was already apparent at 1 ng/ml insulin, it reached near maximal level only at 10,000 ng/ml. IGF I also stimulated DNA synthesis in smooth muscle cells; however, at low concentrations insulin was more efficient in this respect. Human growth hormone was inactive. The data indicate the presence of specific receptors for insulin in bovine aortic smooth muscle cells. These receptors appear to mediate the metabolic activity as well as part of the mitogenic effect of insulin in these cells.

Abstract P110: EBP50 Regulates Vascular Smooth Muscle Cell Growth by Skp2-Mediated Degradation of p21/cip1

2011 ◽  
Vol 109 (suppl_1) ◽  
Author(s):  
Gyun Jee Song ◽  
Stacey Barrick ◽  
Kristen L Leslie ◽  
Nathalie M Fiaschi-Taesch ◽  
Alessandro Bisello
Keyword(s):  
Cell Cycle ◽  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Pdz Domain ◽  
Scaffolding Protein ◽  
Mrna Levels ◽  
Neointima Formation ◽  
Vsmc Proliferation ◽  
Genetic Ablation ◽  
Skp2 Expression

The PDZ domain-containing scaffolding protein, Ezrin-Radixin-Moesin-binding phosphoprotein 50 (EBP50) regulates vascular stenosis following endoluminal vessel injury. Its expression in vascular smooth muscle cells (VSMC) increases after wire injury, and neointima formation is significantly reduced in EBP50 knockout (KO) mice. The molecular mechanisms underlying EBP50 actions in VSMC are unknown. Genetic ablation of EBP50 reduced VSMC proliferation and was associated with increased (5-fold) expression of the cell cycle inhibitor p21cip1 both in vessels and in primary cells. No differences in mRNA levels of p21cip1 were observed in WT and KO cells. However, the half-life of p21cip1 in KO VSMC was significantly longer than in WT VSMC (80 min vs. 45 min) and p21cip1 levels were similar in WT and KO VSMC treated with the proteasome inhibitor MG132. These observations suggest that EBP50 regulates post-translational degradation of p21cip1. The S-phase kinase-associated protein 2 (skp2) is a component of the E3 ligase complex that degrades p21cip1. The C-terminal four amino acids of skp2 (ProSerCysLeu) are a canonical PDZ-binding sequence. Indeed, co-immunoprecipitation and in-gel overlay assays demonstrated the direct interaction between EBP50 and skp2. Mutation of the C-terminal Leu to Ala (L424A-skp2) abrogated the interaction with EBP50. Skp2 expression was significantly lower in KO than in WT cells and inhibition of EBP50 expression by an shRNA lentivirus decreased skp2 expression in WT cells. Moreover, expression of skp2, but not of the mutant L424A-skp2, in WT cells reduced p21cip1 levels. Therefore, EBP50 regulates both expression and activity of skp2 with attendant effects on p21cip1 and VSMC proliferation. Collectively, these experiments show that EBP50, by regulating skp2 and p21cip1 expression, controls VSMC proliferation and the progression of neointima formation. These studies identify a novel function for EBP50 in the direct regulation of the cell cycle and provide a mechanistic basis for the remarkable effect of this scaffolding protein on vascular remodeling.

scholarly journals Perlecan regulates Oct-1 gene expression in vascular smooth muscle cells.

1997 ◽  
Vol 8 (6) ◽  
pp. 999-1011 ◽  
Author(s):  
M C Weiser ◽  
N A Grieshaber ◽  
P E Schwartz ◽  
R A Majack
Keyword(s):  
Gene Expression ◽  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Type Iv Collagen ◽  
Muscle Cells ◽  
Mrna Levels ◽  
Type Iv

Vascular smooth muscle cells (SMCs) are very quiescent in the mature vessel and exhibit a remarkable phenotype-dependent diversity in gene expression that may reflect the growth responsiveness of these cells under a variety of normal and pathological conditions. In this report, we describe the expression pattern of Oct-1, a member of a family of transcription factors involved in cell growth processes, in cultured and in in vivo SMCs. Oct-1 mRNA was undetectable in the contractile-state in vivo SMCs; was induced upon disruption of in vivo SMC-extracellular matrix interactions; and was constitutively expressed by cultured SMCs. Oct-1 transcripts were repressed when cultured SMCs were plated on Engelbreth-Holm-Swarm tumor-derived basement membranes (EHS-BM) but were rapidly induced after disruption of SMC-EHS-BM contacts; reexpression was regulated at the transcriptional level. To identify the EHS-BM component involved in the active repression of Oct-1 mRNA expression, SMCs were plated on laminin, type IV collagen, fibronectin, or perlecan matrices. Oct-1 mRNA levels were readily detectable when SMCs were cultured on matrices composed of laminin, type IV collagen, or fibronectin but were repressed when SMCs were cultured on perlecan matrices. Finally, the Oct-1-suppressing activity of EHS-BM was sensitive to heparinase digestion but not to chondroitinase ABC or hyaluronidase digestion, suggesting that the heparan sulfate side chains of perlecan play a biologically important role in negatively regulating the expression of Oct-1 transcripts.

Length-dependent sensitivity in vascular smooth muscle

1981 ◽  
Vol 241 (4) ◽  
pp. H557-H563 ◽  
Author(s):  
J. M. Price ◽  
D. L. Davis ◽  
E. B. Knauss
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Dose Response ◽  
Length Change ◽  
Maximal Response ◽  
Anterior Tibial Artery ◽  
Response Curves ◽  
Anterior Tibial ◽  
Dose Response Curves ◽  
Best Fit

Dose-response curves were obtained from dog anterior tibial artery rings at various lengths (L) to determine whether sensitivity to norepinephrine (NE) and potassium (K+) depends on arterial circumference. The dose for half maximal response (ED50) was determined by graphical estimation and by calculation from a best fit curve. For both NE and K+: 1) ED50 was lowest (most sensitive) at L for maximum active force (Lmax) and increased significantly as L decreased from Lmax; 2) ED50 at 1.0 and 1.15 Lmax was not significantly different; 3) ED50 of repeated dose-response curves at Lmax was not significantly different; and 4) when the direction of length change was reversed (from decreasing to increasing), the direction of change in ED50 was also reversed (from increasing to decreasing). Change in the dose for 10% maximal response was the same as ED50. The results did not depend on the method of determining ED50 or on whether responses were expressed as absolute values or as relative values. The results show that sensitivity of vascular smooth muscle depends on L and that the length-sensitivity relation is similar to the length-active tension relation. Similarity of results for NE and K+ indicate that length-dependent sensitivity does not depend on the method of stimulation.

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