Vascular smooth muscle Na+-H+ exchanger kinetics and its activation by angiotensin II

1988 ◽  
Vol 254 (6) ◽  
pp. C751-C758 ◽  
Author(s):  
G. A. Vallega ◽  
M. L. Canessa ◽  
B. C. Berk ◽  
T. A. Brock ◽  
R. W. Alexander
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Maximum Velocity ◽  
Kinetic Properties ◽  
Ang Ii ◽  
Intracellular Acidification ◽  
Aortic Smooth Muscle ◽  
Maximal Activation ◽  
Free Media ◽  
Kinetics Of

We have studied the kinetic properties of basal and angiotensin II (ANG II)-stimulated Na+-H+ exchange in cultured rat aortic smooth muscle cells. Initial rates of 22Na+ influx were measured in the presence of ouabain (1 mM) and bumetanide (0.1 mM) with and without amiloride after intracellular acidification by preincubation in Na-free media. The kinetics of amiloride (100 microM)-sensitive Na+ influx were studied under the following conditions: 1) constant intracellular pH (pHi; 6.8) and varying external Na+ (Na+o), which gave a Km of 23.6 +/- 2.0 (SD, n = 3) mM and a maximum velocity (Vmax) of 25 nmol.mg protein-1.min-1 (varying the amiloride concentration gave a Ki of 22 microM for inhibition under these conditions); and 2) constant Na+o (100 mM) and varying pHi (from 7.4 to 6.2), which indicated that amiloride-sensitive Na+ influx was stimulated by cell acidification when an outward H+ gradient was imposed. ANG II-stimulated amiloride-sensitive Na+ influx for up to 30 min with a half-maximal activation 10(-8) M. The pHi dependence from cell pH (pHi 7.2-6.2) of amiloride-sensitive Na+ influx stimulated by ANG II was similar to that of the basal values, a finding indicating that ANG II did not change the affinity of Na+-H+ exchange for intracellular H+. However, at pHi 6.8, ANG II increased the Vmax of amiloride-sensitive Na+ influx from 25 to 33 nmol.mg protein-1.min-1 and markedly decreased the Km for Na+o from 23.6 +/- 7.4 to 3.7 (SD, n = 4; P less than 0.005) mM.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

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

scholarly journals Role of miR-134 in angiotensin II-induced vascular cell pathological changes in atherosclerosis

2021 ◽  
Vol 18 (5) ◽  
pp. 967-973
Author(s):  
Jing Chen ◽  
Qi Hu ◽  
Bofang Zhang ◽  
Xiaopei Liu ◽  
Shuo Yang ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Mtor Pathway ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Ang Ii ◽  
Potential Therapeutic Target ◽  
Aortic Smooth Muscle ◽  
Cell Dysfunction ◽  
Dichlorofluorescein Diacetate

Purpose: To investigate the role of miR-134 in vascular smooth muscle cell dysfunction-related cardiovascular disease. Methods: The effect of miR-134 was evaluated after human aortic smooth muscle cells (HASMCs) were transfected with miR-134 mimics. The expression levels of p-Akt, mechanistic target of rapamycin (mTOR), cleaved caspase-3, p53, and β-actin were evaluated by immunoblotting. Terminal deoxynucleotidyl transferase dUTP nick-end labeling was used to measure cell apoptosis. Reactive oxygen species levels were assayed by fluorescence microscopy after staining with 2’,7’– dichlorofluorescein diacetate. Results: Angiotensin II treatment induced miR-134 expression and Akt/mTOR activation, and inhibited cell viability in HASMCs (p < 0.01). Co-treatment with miRNA-134 reversed Ang II-induced HASMC dysfunction (p < 0.01). Overexpression of miR-134 is protective in Ang II-induced oxidative stress and apoptosis via the Akt/mTOR pathway (p < 0.05). Conclusion: MicroRNA-134 in HASMCs is a potential therapeutic target for preventing Ang II-induced cardiac dysfunction via modulating Akt/mTOR pathway.

scholarly journals Angiotensin II inhibits and alters kinetics of voltage-gated K+ channels of rat arterial smooth muscle

2001 ◽  
Vol 281 (6) ◽  
pp. H2480-H2489 ◽  
Author(s):  
Y. Hayabuchi ◽  
N. B. Standen ◽  
N. W. Davies
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Protein Kinase ◽  
Ang Ii ◽  
Arterial Smooth Muscle ◽  
Pkc Inhibitor ◽  
Voltage Gated ◽  
Kinase C ◽  
Inhibitor Peptide ◽  
Kinetics Of

The vasoconstrictor angiotensin II (ANG II) inhibits several types of K+ channels. We examined the inhibitory mechanism of ANG II on voltage-gated K+ (KV) currents ( I KV ) recorded from isolated rat arterial smooth muscle using patch-clamp techniques. Application of 100 nM ANG II accelerated the activation of I KV but also caused inactivation. These effects were abolished by the AT1 receptor antagonist losartan. The protein kinase A (PKA) inhibitor Rp-cyclic 3′,5′-hydrogen phosphothioate adenosine (100 μM) and an analog of diacylglycerol, 1,2-dioctanyoyl-rac-glycerol (2 μM), caused a significant reduction of I KV . Furthermore, the combination of 5 μM PKA inhibitor peptide 5–24 (PKA-IP) and 100 μM protein kinase C (PKC) inhibitor peptide 19–27 (PKC-IP) prevented the inhibition by ANG II, although neither alone was effective. The ANG II effect seen in the presence of PKA-IP remained during addition of the Ca2+-dependent PKC inhibitor Gö6976 (1 μM) but was abolished in the presence of 40 μM PKC-ε translocation inhibitor peptide. These results demonstrate that ANG II inhibits KVchannels through both activation of PKC-ε and inhibition of PKA.

scholarly journals Induction of the proto-oncogene c-jun by angiotensin II.

1990 ◽  
Vol 10 (10) ◽  
pp. 5536-5540 ◽  
Author(s):  
A J Naftilan ◽  
G K Gilliland ◽  
C S Eldridge ◽  
A S Kraft
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Cell Growth ◽  
Ang Ii ◽  
Enhancer Element ◽  
Aortic Smooth Muscle ◽  
Important Mediator ◽  
Smooth Muscle Cell Growth ◽  
Rapid Activation

Angiotensin (Ang) II causes hypertrophy of rat aortic smooth muscle cells in culture and results in the rapid activation of c-fos. This study demonstrated that Ang II also activated c-jun and, in addition, could activate the AP-1 enhancer element. These data add support for a role of Ang II as an important mediator of vascular smooth muscle cell growth.

Angiotensin decreases cyclic GMP accumulation produced by atrial natriuretic factor

1987 ◽  
Vol 253 (1) ◽  
pp. C147-C150 ◽  
Author(s):  
J. B. Smith ◽  
T. M. Lincoln
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Cyclic Gmp ◽  
Atrial Natriuretic Factor ◽  
Phosphodiesterase Inhibitor ◽  
Ionophore A23187 ◽  
Ang Ii ◽  
Aortic Smooth Muscle ◽  
Natriuretic Factor ◽  
Atrial Natriuretic

Atrial natriuretic factor (ANF) produced rapid increases in cyclic GMP (cGMP) in cultured aortic smooth muscle cells. Angiotensin II (ANG II) markedly decreased the accumulation of cGMP that was evoked by ANF. Arginine vasopressin and ATP, which evoke transient increases in free Ca2+ similarly to ANG II, also inhibited cGMP accumulation. The effect of the calcium mobilizing neurohormones was mimicked by the divalent cation ionophore, A23187. The cyclic nucleotide phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine, prevented ANG II from inhibiting ANF-evoked cGMP accumulation. ANG II also inhibited cGMP accumulation induced by nitroprusside, a compound that activates cytosolic guanylate cyclase. These findings support the hypothesis that ANG II decreases cGMP accumulation by stimulating cGMP hydrolysis, apparently via a Ca2+-activated cGMP phosphodiesterase.

Expression of myosin regulatory light-chain isoforms and regulation of phosphorylation in smooth muscle

1993 ◽  
Vol 264 (6) ◽  
pp. C1466-C1472 ◽  
Author(s):  
P. L. Monical ◽  
G. K. Owens ◽  
R. A. Murphy
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Cell Density ◽  
Cellular Functions ◽  
Growth State ◽  
Regulatory Light Chains ◽  
Aortic Smooth Muscle ◽  
Mlc20 Phosphorylation ◽  
Differential Phosphorylation ◽  
Kinetics Of

Our objectives were to 1) determine how growth state and cell density affect the expression of the smooth muscle (SM) and nonmuscle (NM) isoforms of the 20-kDa myosin regulatory light chains (MLC20) in cultured rat aortic smooth muscle cells (SMC) and 2) to determine whether angiotensin II stimulates differential phosphorylation of SM and NM MLC20 isoforms in an effort to assess whether the SM and NM isoforms may subserve different cellular functions. The results demonstrated that changes in the SM MLC20 isoform content were inversely correlated with cell growth but independent of cell density. MLC20 phosphorylation levels were 20.8 +/- 2.9 and 19.4 +/- 3.7% for SM and NM isoforms, respectively, in unstimulated, substrate-attached SMC. Angiotensin II transiently elevated phosphorylation levels of both the SM and NM MLC20 isoforms to 60-70%. No differences in either the magnitude or the kinetics of phosphorylation were observed for the SM vs. NM isoforms. Forskolin, 3-isobutyl-1-methylxanthine, or isoproterenol treatment led to parallel dephosphorylation of the SM- and NM-specific isoforms followed by depolymerization of stress fibers and cell arborization. The studies provide evidence that growth arrest of cultured SMC enhances expression of cell-specific/-selective proteins characteristic of differentiated SM. However, there was no evidence for differential phosphorylation changes of SM and NM MLC20 isoforms in response to activating or relaxing agents as expected if these isoforms subserve different cellular functions.

Induction of the proto-oncogene c-jun by angiotensin II

1990 ◽  
Vol 10 (10) ◽  
pp. 5536-5540
Author(s):  
A J Naftilan ◽  
G K Gilliland ◽  
C S Eldridge ◽  
A S Kraft
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Cell Growth ◽  
Ang Ii ◽  
Enhancer Element ◽  
Aortic Smooth Muscle ◽  
Important Mediator ◽  
Smooth Muscle Cell Growth ◽  
Rapid Activation

Angiotensin (Ang) II causes hypertrophy of rat aortic smooth muscle cells in culture and results in the rapid activation of c-fos. This study demonstrated that Ang II also activated c-jun and, in addition, could activate the AP-1 enhancer element. These data add support for a role of Ang II as an important mediator of vascular smooth muscle cell growth.

scholarly journals Effects of angiotensin II and of phorbol ester on protein kinase C activity and on prostacyclin production in cultured rat aortic smooth-muscle cells

1989 ◽  
Vol 259 (2) ◽  
pp. 477-483 ◽  
Author(s):  
U Lang ◽  
M B Vallotton
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase C ◽  
Angiotensin Ii ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Ang Ii ◽  
Aortic Smooth Muscle Cells ◽  
Aortic Smooth Muscle ◽  
Kinase C ◽  
Prostacyclin Production

The role of the Ca2+-sensitive phospholipid-dependent protein kinase C (PKC) was studied in cultured rat aortic smooth-muscle cells, known to respond to angiotensin II (Ang II) by producing prostacyclin, determined by the release of 6-oxo-prostaglandin F1 alpha. PKC activity was measured in the cytosol and the solubilized membrane fraction after DEAE-cellulose chromatography using a linear NaCl gradient. Ang II stimulated the activity of PKC in the cytosolic and in the membrane fractions of aortic smooth-muscle cells. These increases in PKC activity were concentration-dependent and occurred rapidly, reaching a plateau within 10 min. In contrast, phorbol 12-myristate 13-acetate (PMA) rapidly decreased cytosolic PKC activity and at the same time increased membrane PKC activity to reach a plateau after 20 min. Cytosolic PKC activity from control and Ang II-stimulated cells was found to be less dependent on [Ca2+] than was the highly [Ca2+]-dependent membrane PKC activity from the same cells. In contrast, membrane PKC activity from PMA-treated cells was largely [Ca2+]-independent. In the presence of 10 nM-PMA, the sensitivity of cultured smooth-muscle cells towards Ang II was increased, and maximal values of Ang II-induced prostacyclin production were enhanced by about 60%. In cells incubated with both Ang II and PMA, an additive effect on membrane PKC activity was observed, whereas cytosolic PKC activity was suppressed as in cells treated with PMA alone. These results suggest that an increase of the membrane, but not the cytosolic, PKC activity represents a positive signal in the prostacyclin production induced by Ang II stimulation of aortic smooth-muscle cells. PMA seems to induce a state of activation of membrane PKC which does not need increased intracellular [Ca2+] to be fully expressed, whereas Ang II-stimulated membrane PKC activity requires higher Ca2+ concentrations. The possibility exists that the addition of both signals leads to the augmentation of Ang II-stimulated prostacyclin production.

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