Fatty acid inhibition of angiotensin II-stimulated inositol phosphates in smooth muscle cells

1993 ◽  
Vol 264 (2) ◽  
pp. H595-H603
Author(s):  
M. E. Ullian
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Smooth Muscle Cells ◽  
Receptor Binding ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Muscle Cells ◽  
Ang Ii ◽  
Guanine Nucleotide Binding Protein ◽  
Cellular Incorporation

Inositol phosphate (InsP) responses to angiotensin II (ANG II) stimulation were measured in cultured rat vascular smooth muscle cells (VSMC) incubated with and without fatty acids (FA). VSMC were washed after 24 h of FA incubation to achieve cellular incorporation of FA yet eliminate ambient FA. Incubation with eicosapentaenoic acid (EPA)-supplemented medium resulted in concentration-dependent incorporation of EPA and depletion of arachidonic acid in VSMC membranes. Incubation with EPA, but not other FA, resulted in inhibition of ANG II-stimulated InsP formation (29% inhibition with 100 microM EPA). In contrast, InsP formation in response to guanine nucleotide-binding protein stimulation was not affected by EPA. ANG II receptor binding to membranes prepared from EPA-loaded VSMC was 18% lower than binding in membranes from sham-loaded cells. In other studies, VSMC were exposed acutely to FA to avoid cellular incorporation. Exposure to all FA resulted in concentration-dependent reductions in ANG II binding and ANG II-stimulated InsP formation; binding affinity was reduced without changes in receptor density. We conclude that ANG II-stimulated InsP formation is modestly and selectively inhibited by EPA incorporation and more profoundly inhibited by acute exposure to many FA via interference with ANG II receptor binding.

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.

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)

Stored calcium modulates inositol phosphate synthesis in cultured smooth muscle cells

1992 ◽  
Vol 263 (2) ◽  
pp. C535-C539 ◽  
Author(s):  
D. M. Berman ◽  
W. F. Goldman
Keyword(s):  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Smooth Muscle Cells ◽  
Inverse Relationship ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Muscle Cells ◽  
Inhibitory Effect ◽  
A7r5 Cells ◽  
Cultured Smooth Muscle Cells

Cytosolic Ca2+ concentrations ([Ca2+]cyt) and [3H]inositol phosphates ([3H]InsP) were correlated while varying the Ca2+ content of the sarcoplasmic reticulum (SR) in cultured A7r5 cells at rest and during activation with [Arg8]-vasopressin (AVP). Thapsigargin (TG) raised and superfusion with 0 Ca2+ lowered [Ca2+]cyt, but both treatments decreased SR Ca2+ and AVP-evoked Ca2+ transients. Neither TG nor 0 Ca2+ affected basal [3H]InsP, but both treatments increased AVP-evoked synthesis of [3H]InsP. Exposure for several minutes to 40 mM K+ solution, BAY K 8644, or low-Na+ solution all elevated [Ca2+]cyt and, thereby, increased SR Ca2+, as manifested by augmented AVP-evoked Ca2+ transients. In all three cases, AVP-evoked, but not basal, [3H]InsP were reduced. The inhibitory effect of 40 mM K+ on AVP-evoked [3H]InsP synthesis was blocked when SR Ca2+ uptake was prevented by TG. Brief (30-s) exposures to 40 mM K+, which elevated [Ca2+]cyt but not SR Ca2+ loading, did not modify AVP-evoked [3H]InsP synthesis or Ca2+ transients. These results demonstrate an inverse relationship between SR Ca2+ content and evoked [3H]-InsP synthesis. Moreover, they suggest that SR Ca2+ may serve as a signal that modulates sarcolemmal [3H]InsP formation.

Mechanism of angiotensin II-induced arachidonic acid metabolite release in aortic smooth muscle cells: involvement of phospholipase D

1997 ◽  
Vol 136 (2) ◽  
pp. 207-212 ◽  
Author(s):  
Junji Shinoda ◽  
Osamu Kozawa ◽  
Atsushi Suzuki ◽  
Yasuko Watanabe-Tomita ◽  
Yutaka Oiso ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Smooth Muscle Cells ◽  
Phospholipase D ◽  
Muscle Cells ◽  
Dependent Manner ◽  
Ang Ii ◽  
Aortic Smooth Muscle Cells ◽  
Aortic Smooth Muscle

Abstract In a previous study, we have shown that angiotensin II (Ang II) activates phosphatidylcholinehydrolyzing phospholipase D due to Ang II-induced Ca2+ influx from extracellular space in subcultured rat aortic smooth muscle cells. In the present study, we have investigated the role of phospholipase D in Ang II-induced arachidonic acid (AA) metabolite release and prostacyclin synthesis in subcultured rat aortic smooth muscle cells. Ang II significantly stimulated AA metabolite release in a concentration-dependent manner in the range between 1 nmol/l and 0·1 μmol/l. d,l-Propranolol hydrochloride (propranolol), an inhibitor of phosphatidic acid phosphohydrolase, significantly inhibited the Ang II-induced release of AA metabolites. The Ang II-induced AA metabolite release was reduced by chelating extracellular Ca2+ with EGTA. Genistein, an inhibitor of protein tyrosine kinases, significantly suppressed the Ang II-induced AA metabolite release. 1,6-Bis-(cyclohexyloximinocarbonylamino)-hexane (RHC-80267), a potent and selective inhibitor of diacylglycerol lipase, significantly inhibited the Ang II-induced AA metabolite release. Both propranolol and RHC-80267 inhibited the Ang II-induced synthesis of 6-keto-prostaglandin F1α, a stable metabolite of prostacyclin. The synthesis was suppressed by genistein. These results strongly suggest that the AA metabolite release induced by Ang II is mediated, at least in part, through phosphatidylcholine hydrolysis by phospholipase D activation in aortic smooth muscle cells. European Journal of Endocrinology 136 207–212

THE ROLE OF CALCIUM (CA2+) IN MODULATION OF SMOOTH MUSCLE CELLS REACTIVITY TO ANGIOTENSIN II (ANG II) DURING ISCHEMIA/REPERFUSION (I/R).

2008 ◽  
Vol 86 (Supplement) ◽  
pp. 736
Author(s):  
M Slupski ◽  
K Szadujkis-Szadurska ◽  
R Szadujkis-Szadurski ◽  
M Jasinski ◽  
G Grzesk
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Smooth Muscle Cells ◽  
Ischemia Reperfusion ◽  
Muscle Cells ◽  
Ang Ii

Bradykinin and angiotensin II: activation of protein kinase C in arterial smooth muscle

1994 ◽  
Vol 266 (5) ◽  
pp. C1406-C1420 ◽  
Author(s):  
B. S. Dixon ◽  
R. V. Sharma ◽  
T. Dickerson ◽  
J. Fortune
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase C ◽  
Angiotensin Ii ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Ang Ii ◽  
Kinase C ◽  
Membrane Bound

The effects of bradykinin (BK) and angiotensin II (ANG II) were compared in cultured rat mesenteric arterial smooth muscle cells. BK and ANG II activated a phosphoinositide-specific phospholipase C, leading to the rapid release of [3H]inositol phosphates, an increase in intracellular calcium, and formation of sn-1,2-diacylglycerol (DAG). DAG formation was biphasic with a transient peak at 5 s followed by a sustained increase from 60 to 600 s. The BK-mediated increases in inositol triphosphate and DAG were dose dependent with half-maximal increases at concentrations of 5 and 2 nM, respectively. Both hormones were found to activate protein kinase C (PKC) as assessed by phosphorylation of the 68- to 72-kDa intracellular PKC substrate myristoylated alanine-rich C kinase substrate. However, despite similar phosphorylation of this substrate, only ANG II produced a significant increase in membrane-bound PKC activity. The mechanism accounting for the inability of BK to increase membrane-bound PKC activity is unclear. Our studies excluded differential translocation of PKC to the nuclear membrane, production of an inhibitor of membrane-bound PKC activity, and expression of BK and ANG II receptors on different cells as the mechanism. Vascular smooth muscle cells were found to express at least four different PKC isozymes: alpha, delta, zeta, and a faint band for epsilon. All of the isozymes except zeta-PKC were translocated by treatment with the phorbol ester 4 beta-phorbol 12-myristate 13-acetate. However, neither ANG II nor BK produced significant translocation of any measured isozyme; therefore, we could not exclude the possibility that ANG II and BK activate different isozymes of PKC. Both hormones were found to have a similar small and inconsistent effect in stimulating [3H]thymidine incorporation. These observations demonstrate that BK and ANG II have similar biochemical effects on vascular smooth muscle cells and imply that, in selected vessels, the vasodilatory effects of BK mediated by the endothelium may be partially counterbalanced by a vasoconstrictor effect on the underlying vascular smooth muscle cells.

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.

Morphological and biochemical analysis of angiotensin II internalization in cultured rat aortic smooth muscle cells

1993 ◽  
Vol 264 (1) ◽  
pp. C179-C188 ◽  
Author(s):  
K. M. Anderson ◽  
T. Murahashi ◽  
D. E. Dostal ◽  
M. J. Peach
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Biologically Active ◽  
Gold Complex ◽  
Ang Ii ◽  
Coated Pits ◽  
Transmission Electron ◽  
Entire Cell

The intracellular pathway and kinetics of angiotensin II (ANG II) internalization are not well understood. We developed a biologically active ANG II-colloidal gold complex to qualitatively examine, by transmission electron microscopy, the ultrastructural details of ANG II binding and internalization in cultured rat aortic vascular smooth muscle cells (VSMC). To quantitatively evaluate ANG II internalization, we analyzed intracellular accumulation of 125I-labeled ANG II. These studies show that ANG II is internalized by VSMC in a time- and temperature-dependent fashion with a half time of < 2 min at 37 degrees C. Initially, ANG II binds diffusely over the entire cell surface. After binding, the ANG II receptors aggregate in coated pits that transform into small intracellular vesicles. By 60 min after internalization, gold particles are evident within large lysosome-like vesicles deep within the cell. ANG II-gold binding and internalization were selective: control probe (no ANG II) did not internalize; losartan potassium effectively competed for ANG II-gold binding and internalization.

Angiotensin II enhancement of hormone-stimulated cAMP formation in cultured vascular smooth muscle cells

1993 ◽  
Vol 264 (1) ◽  
pp. H86-H96 ◽  
Author(s):  
S. W. Kubalak ◽  
J. G. Webb
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Protein Kinase ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Ang Ii ◽  
Camp Formation ◽  
Camp Stimulation

The mechanism by which angiotensin II (ANG II) potentiates hormone-induced adenosine 3',5'-cyclic monophosphate (cAMP) formation was studied in cultured rat vascular smooth muscle cells. Incubation of cells for 60 s with 100 nM ANG II produced a two- to threefold enhancement of cAMP stimulation when coupled with isoproterenol, prostaglandin I2, or adenosine. ANG II also enhanced cAMP formation when adenylyl cyclase was stimulated directly with forskolin or activated through the stimulatory guanyl nucleotide-binding protein (Gs) with cholera toxin. Forskolin stimulation was increased by only 40%, but cholera toxin-stimulated cAMP formation was doubled. Activation of protein kinase C with phorbol 12-myristate 13-acetate (PMA) enhanced isoproterenol-stimulated cAMP by 51%, but inhibitors of protein kinase activation had little effect on ANG II enhancement of cAMP production. However, use of PMA to cause feedback inhibition of D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] formation blocked the effect of ANG II on agonist-stimulated cAMP formation, and the time course for this effect of PMA paralleled its inhibitory effect on Ins(1,4,5)P3 production. Furthermore, chelation of intracellular Ca2+ or treatment with calmodulin antagonists also diminished the synergism between ANG II and isoproterenol for cAMP stimulation. The results indicate that ANG II enhances cAMP formation in vascular smooth muscle cells by facilitating the interaction between activated Gs and adenylyl cyclase. In addition, the data suggest that this effect of ANG II is directly related to Ins(1,4,5)P3 stimulation and appears to involve a Ca(2+)-calmodulin-dependent mechanism.

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