Role of Na(+)-Ca2+ exchange in agonist-induced changes in cytosolic Ca2+ in vascular smooth muscle cells

1994 ◽  
Vol 266 (3) ◽  
pp. C794-C799 ◽  
Author(s):  
Z. Zhu ◽  
M. Tepel ◽  
M. Neusser ◽  
W. Zidek
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Free Calcium ◽  
Ang Ii ◽  
Protein Kinase C Activity ◽  
Wistar Kyoto ◽  
Induced Changes

Changes in cytosolic free calcium concentration ([Ca2+]i) induced by angiotensin II (ANG II), arginine vasopressin (AVP), angiotensin III (ANG III), norepinephrine (NE), or thapsigargin were investigated after inhibition of the Na(+)-Ca2+ exchange in vascular smooth muscle cells (VSMC) from Wistar-Kyoto rats by use of the fluorescent dye technique. The ANG II-induced peak [Ca2+]i increase was significantly enhanced after inhibition of Na(+)-Ca2+ exchange by NiCl2 or 1,3-dimethyl-2-thiourea (DMTU): control, 99 +/- 9 (SE) nM (n = 64); NiCl2, 181 +/- 23 nM (n = 23; P < 0.01); DMTU, 182 +/- 35 nM (n = 10; P < 0.05). In the absence of external calcium, the inhibition of the Na(+)-Ca2+ exchange by NiCl2 also enhanced the ANG II-induced [Ca2+]i increase. Inhibition of Na(+)-Ca2+ exchange by removal of external sodium, which was replaced by choline, augmented the ANG II-induced [Ca2+]i increase to 174 +/- 26 nM (n = 11; P < 0.05 compared with control). The inhibition of the protein kinase C activity by isoquinoline-sulfonyl-O-2-methylpiperazine blocked the enhancing effect of NiCl2 on ANG II-induced [Ca2+]i increase. The inhibition of the Na(+)-Ca2+ exchange did not enhance the increase in [Ca2+]i induced by ANG III, NE, or thapsigargin. The AVP-induced changes in [Ca2+]i were not significantly different in the presence or absence of NiCl2. It is concluded that the recovery of resting [Ca2+]i after stimulation by ANG II is mediated by calcium efflux via the Na(+)-Ca2+ exchange.(ABSTRACT TRUNCATED AT 250 WORDS)

SAM68: a downstream target of angiotensin II signaling in vascular smooth muscle cells in genetic hypertension

2004 ◽  
Vol 286 (5) ◽  
pp. H1954-H1962 ◽  
Author(s):  
Mohammed El Mabrouk ◽  
Quy N. Diep ◽  
Karim Benkirane ◽  
Rhian M. Touyz ◽  
Ernesto L. Schiffrin
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Kinase Activity ◽  
Muscle Cells ◽  
Regulatory Subunit ◽  
Ang Ii ◽  
Wistar Kyoto

We investigated whether phosphatidylinositol 3-kinase (PI3K) and 68-kDa Src associated during mitosis (SAM68) are involved in angiotensin II (ANG II) growth signaling in vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats (SHR). PI3K activity was assessed by measuring the phosphorylation of the regulatory subunit p85α and kinase activity of the catalytic 110-kDa subunit of PI3K. The PI3K-SAM68 interaction was assessed by coimmunoprecipitation, and SAM68 activity was evaluated by poly(U) binding. SAM68 expression was manipulated by SAM68 antisense oligonucleotide transfection. VSMC growth was evaluated by measuring [3H]leucine and [3H]thymidine incorporation as indexes of protein and DNA synthesis, respectively. ANG II increased the phosphorylation of p85α and kinase activity of the 110-kDa PI3K subunit in VSMCs from SHR and transiently increased p85α-SAM68 association. In Wistar-Kyoto (WKY) rat cells, ANG II increased SAM68 phosphorylation without influencing poly(U) binding. In SHR, ANG II did not influence SAM68 phosphorylation but increased SAM68 binding to poly(U). ANG II stimulated phosphoinositol phosphate synthesis by PI3K in SAM68 immunoprecipitates in both groups, with significantly enhanced effects in SHR. Inhibition of PI3K, using the selective inhibitor LY-294002, and downregulation of SAM68, by antisense oligonucleotides, significantly decreased ANG II-stimulated incorporation of [3H]leucine and [3H]thymidine in VSMCs, showing the functional significance of PI3K and SAM68. Our data demonstrate that PI3K and SAM68 are involved in ANG II signaling and that SAM68 is differentially regulated in VSMCs from SHR. These processes may contribute to the enhanced ANG II signaling and altered VSMC growth in SHR.

scholarly journals RACK1 regulates angiotensin II-induced contractions of SHR preglomerular vascular smooth muscle cells

2017 ◽  
Vol 312 (4) ◽  
pp. F565-F576 ◽  
Author(s):  
Xiao Zhu ◽  
Edwin K. Jackson
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Scaffolding Protein ◽  
Cell Fractionation ◽  
Ang Ii ◽  
Spontaneously Hypertensive ◽  
Wistar Kyoto

The preglomerular microcirculation of spontaneously hypertensive rats (SHR) is hypersensitive to angiotensin (ANG) II, and studies have shown that this is likely due to enhanced coincident signaling between G protein subunits αq (Gαq; released by ANG II) and βγ (Gβγ; released by Gi-coupled receptors) to active phospholipase C (PLC). Here we investigated the molecular basis for the enhanced coincident signaling between Gβγ and Gαq in SHR preglomerular vascular smooth muscle cells (PGVSMCs). Because receptor for activated C kinase 1 (RACK1; a scaffolding protein) organizes interactions between Gβγ, Gαq, and PLC, we included RACK1 in this investigation. Cell fractionation studies demonstrated increased levels of membrane (but not cytosolic) Gβ, Gαq, PLCβ3, and RACK1 in SHR PGVSMCs compared with Wistar-Kyoto rat PGVSMCs. In SHR PGVSMCs, coimmunoprecipitation demonstrated RACK1 binding to Gβ and PLCβ3, but only at cell membranes. Pertussis toxin (which blocks Gβγ) and U73122 (which blocks PLC) reduced membrane RACK1; however, RACK1 knockdown (shRNA) did not affect membrane levels of Gβ, Gαq, or PLCβ3. In a novel gel contraction assay, RACK1 knockdown in SHR PGVSMCs attenuated contractions to ANG II and abrogated the ability of neuropeptide Y (which signals via Gβγ) to enhance ANG II-induced contractions. We conclude that in SHR PGVSMCs the enlarged pool of Gβγ and PLCβ3 recruits RACK1 to membranes and RACK1 then organizes signaling. Consequently, knockdown of RACK1 prevents coincident signaling between ANG II and the Gi pathway. This is the first study to implicate RACK1 in vascular smooth muscle cell contraction and suggests that RACK1 inhibitors could be effective cardiovascular drugs.

Kinetics of Na+/H+ exchange in vascular smooth muscle cells from WKY and SHR: effects of phorbol ester

1995 ◽  
Vol 268 (1) ◽  
pp. C14-C20 ◽  
Author(s):  
G. Hoffmann ◽  
Y. Ko ◽  
A. Sachinidis ◽  
B. O. Gobel ◽  
H. Vetter ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Maximal Activity ◽  
Hill Coefficient ◽  
Kinetic Properties ◽  
Wistar Kyoto ◽  
Kinetics Of

The kinetic properties of Na+/H+ exchange were investigated in vascular smooth muscle cells (VSMC) in culture from normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). Antiport activity was measured in 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein-loaded cells after nigericin-induced cytosolic acidification. Studies were performed without (control) and with pretreatment of the cells with phorbol 12-myristate 13-acetate (PMA; 200 nM). Na+/H+ exchange markedly differed between the two strains with lower Hill coefficients [1.56 +/- 0.17 (SE) vs. 2.62 +/- 0.36] and higher maximal activity (Vmax) values (55.85 +/- 5.24 vs. 31.11 +/- 2.38 mmol H+.l-1.min-1) in SHR compared with WKY cell lines. PMA markedly altered the antiport kinetics in WKY VSMC with a decrease in the Hill coefficient (1.75 +/- 0.14) without affecting Vmax (31.88 +/- 1.55 mmol H+.l-1.min-1). In VSMC from SHR, PMA had no effect on the kinetic variables investigated. Thus two kinetic abnormalities are present with respect to Na+/H+ antiport activity in VSMC from SHR compared with WKY, i.e., increased Vmax and decreased Hill coefficient. The observation that PMA does not affect the kinetics of the Na+/H+ antiport in VSMC from SHR suggests a marked degree of antiporter prestimulation in this animal model of genetic hypertension.

scholarly journals Cyclosporin A augments angiotensin II-stimulated rise in intracellular free calcium in vascular smooth muscle cells

1987 ◽  
Vol 248 (3) ◽  
pp. 883-887 ◽  
Author(s):  
J Pfeilschifter ◽  
U T Rüegg
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Cyclosporin A ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Immunosuppressive Drug ◽  
Free Calcium ◽  
Cytosolic Free Calcium

Pretreatment of rat vascular smooth muscle cells with the immunosuppressive drug cyclosporin A caused concentration- and time-dependent increases in both the amplitude and duration of the angiotensin II-induced rise in cytosolic free calcium, as measured with quin 2. Cyclosporin A had no significant effect on basal quin 2 fluorescence. However, cyclosporin A increased the basal 45Ca2+ influx. This stimulation of 45Ca2+ influx was not blocked by nifedipine (10(-6) M). Cyclosporin A also augmented the angiotensin II-stimulated influx and efflux of 45Ca2+. These results demonstrate that cyclosporin A increases the permeability of the plasma membrane for Ca2+ and also augments the angiotensin II-induced increases in cytosolic free calcium.

Angiotensin II modulates frizzled-2 receptor expression in rat vascular smooth muscle cells

2005 ◽  
Vol 108 (6) ◽  
pp. 523-530 ◽  
Author(s):  
Giovanna CASTOLDI ◽  
Serena REDAELLI ◽  
Willy M. M. van de GREEF ◽  
Cira R. T. di GIOIA ◽  
Giuseppe BUSCA ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Ang Ii ◽  
Aortic Smooth Muscle

Ang II (angiotensin II) has multiple effects on vascular smooth muscle cells through the modulation of different classes of genes. Using the mRNA differential-display method to investigate gene expression in rat aortic smooth muscle cells in culture in response to 3 h of Ang II stimulation, we observed that Ang II down-regulated the expression of a member of the family of transmembrane receptors for Wnt proteins that was identified as Fzd2 [Fzd (frizzled)-2 receptor]. Fzds are a class of highly conserved genes playing a fundamental role in the developmental processes. In vitro, time course experiments demonstrated that Ang II induced a significant increase (P<0.05) in Fzd2 expression after 30 min, whereas it caused a significant decrease (P<0.05) in Fzd2 expression at 3 h. A similar rapid up-regulation after Ang II stimulation for 30 min was evident for TGFβ1 (transforming growth factor β1; P<0.05). To investigate whether Ang II also modulated Fzd2 expression in vivo, exogenous Ang II was administered to Sprague–Dawley rats (200 ng·kg−1 of body weight·min−1; subcutaneously) for 1 and 4 weeks. Control rats received normal saline. After treatment, systolic blood pressure was significantly higher (P<0.01), whereas plasma renin activity was suppressed (P<0.01) in Ang II- compared with the saline-treated rats. Ang II administration for 1 week did not modify Fzd2 expression in aorta of Ang II-treated rats, whereas Ang II administration for 4 weeks increased Fzd2 mRNA expression (P<0.05) in the tunica media of the aorta, resulting in a positive immunostaining for fibronectin at this time point. In conclusion, our data demonstrate that Ang II modulates Fzd2 expression in aortic smooth muscle cells both in vitro and in vivo.

scholarly journals Nox5 in Vascular Smooth Muscle Cells Mediates Ang II‐Induced Renal Fibrosis and Inflammation

2021 ◽  
Vol 35 (S1) ◽  
Author(s):  
Augusto Montezano ◽  
Francisco Rios ◽  
Livia Camargo ◽  
Roberto Palacios‐Ramirez ◽  
Antoine Tarjus ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Renal Fibrosis ◽  
Muscle Cells ◽  
Ang Ii

K depletion alters angiotensin II receptor expression in vascular smooth muscle cells

1990 ◽  
Vol 258 (5) ◽  
pp. C849-C854 ◽  
Author(s):  
S. L. Linas ◽  
R. Marzec-Calvert ◽  
M. E. Ullian
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Receptor Expression ◽  
Ang Ii ◽  
Surface Receptors ◽  
K Depletion

Dietary K depletion (KD) results in increases in the number of angiotensin II (ANG II) receptors and prevents ANG II-induced downregulation of ANG II receptors in membrane preparations of vessels from KD animals. Because dietary KD results in changes in factors other than K, we K depleted vascular smooth muscle cells (VSMC) in culture to determine the specific effects of KD on ANG II receptor expression and processing. Scatchard analysis of ANG II uptake at 4 degrees C revealed that the number of surface receptors was increased by 37% in cells in which K had been reduced by 45%. This increase also occurred in the presence of cycloheximide. To determine the effect of KD on receptor processing, we measured the number of surface receptors after exposure to ANG II in concentrations sufficient to cause down-regulation. After 30-min exposure to ANG II, the number of surface receptors was reduced by 63% in control cells but only 33% in KD cells. Thirty minutes after withdrawing ANG II, surface binding returned to basal levels in control cells but was still reduced by 20% in KD cells. To determine the functional significance of impaired receptor processing, we measured ANG II uptake at 21 degrees C. Uptake at 21 degrees C depends on the functional number of receptors, i.e., the absolute number of surface receptors and the rate at which receptors are recycled to the surface after ANG II binding. ANG II uptake at 21 degrees C was reduced by 50% in KD cells.(ABSTRACT TRUNCATED AT 250 WORDS)

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