Effects of intracellular alkalinization on resting and agonist-induced vascular tone

To evaluate the influence of intracellular alkalinization on basal and agonist-induced vascular tone, we studied the effect of NH4Cl on rat aorta. NH4Cl induced a gradually developing contraction in a dose-dependent manner. Although the contractile response to 20 mM NH4Cl was associated with a latent period (LP) of 23.4 +/- 2.8 min, intracellular pH (pHi) measurements in cultured rat aortic smooth muscle cells showed that NH4Cl-induced intracellular alkalinization was immediate and transient, returning to basal pHi levels in about 30-35 min. Agents that elevate Ca2+, such as A23187 and high KCl, significantly reduced the LP associated with 20 mM NH4Cl-induced contraction. NH4Cl-induced contractions were sensitive to extracellular Ca2+ removal and to the addition of forskolin (1 microM); however, NH4Cl by itself did not cause Ca2+-influx as shown by 45Ca-uptake studies. Addition of 20 mM NH4Cl to precontracted tissues resulted in a transient relaxation, which was complete in approximately 10 min, followed by a contraction above the original level of tone. NH4Cl pretreatment caused time-dependent alterations in both the rapid and slow phases of phenylephrine and angiotensin II contractions. Rapid-phase of phenylephrine and angiotensin II contractions. Rapid-phase responses were diminished at shorter NH4Cl incubation times (10 min), whereas slow-phase response was augmented after a longer incubation (20 min). Overall, the vasorelaxant and vasoconstrictor effects induced by NH4Cl suggest a complex relationship between intracellular alkalinization and arterial contractility.

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Potentiation of angiotensin II-stimulated vascular contraction by lithium

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1995.268.5.h2009 ◽

1995 ◽

Vol 268 (5) ◽

pp. H2009-H2016

Author(s):

M. E. Ullian ◽

L. G. Walsh ◽

K. C. Wong ◽

C. J. Allan

Keyword(s):

Angiotensin Ii ◽

Inositol Phosphate ◽

Cytosolic Calcium ◽

Rat Aorta ◽

Dependent Manner ◽

Ang Ii ◽

Concentration Dependent Manner ◽

Adrenergic Agents ◽

Phosphoinositide Signaling ◽

Protein Kinase C Inhibitor

Previous studies have suggested that lithium prolongs or enhances vascular contractions stimulated by alpha-adrenergic agents. The present study was performed to determine whether a similar phenomenon occurs with angiotensin II (ANG II)-stimulated contractions and whether this phenomenon results from interactions with the phosphoinositide signaling system. Contractions of rat aortic rings with 100 nM ANG II were 38% greater in the presence of 20 mM LiCl than in its absence (0.47 +/- 0.07 vs. 0.34 +/- 0.05 g tension/mg dry tissue wt, P < 0.01). The effects of lithium on inositol phosphate responses, diacylglycerol responses, and intracellular calcium concentration on single or repeated stimulations with ANG II were then examined in vascular smooth muscle cells cultured from rat aorta. Cells exposed twice to 100 nM ANG II contained 50% lower inositol trisphosphate levels (InsP3) and 10% lower diacylglycerol levels than cells exposed to ANG II only once. LiCl or lithium acetate abolished these desensitizations in a concentration-dependent manner. Similarly, InsP3 and diacylglycerol responses to a single exposure of ANG II were heightened by lithium (by 75 and 25%, respectively), and the duration of the responses was prolonged by lithium (5- and 2-fold, respectively). In contrast, ANG II-stimulated calcium transients were not enhanced or prolonged by lithium, nor was desensitization of ANG II-stimulated cytosolic calcium mobilization upon serial exposures abolished by lithium. When ring contraction studies were repeated in the presence of the protein kinase C inhibitor staurosporine (150 nM), lithium no longer potentiated ANG II contractions [0.38 +/- 0.03 (control) vs. 0.35 +/- 0.06 g tension/mg dry tissue wt (lithium)].(ABSTRACT TRUNCATED AT 250 WORDS)

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

Acta Endocrinologica ◽

10.1530/eje.0.1360207 ◽

1997 ◽

Vol 136 (2) ◽

pp. 207-212 ◽

Cited By ~ 6

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

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ERK activation contributes to regulation of spontaneous contractile tone via superoxide anion in isolated rat aorta of angiotensin II-induced hypertension

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00388.2006 ◽

2007 ◽

Vol 292 (6) ◽

pp. H2997-H3005 ◽

Cited By ~ 19

Author(s):

Lili Ding ◽

Alexander Chapman ◽

Ryan Boyd ◽

Hui Di Wang

Keyword(s):

Angiotensin Ii ◽

Signaling Pathway ◽

Superoxide Anion ◽

Rat Aorta ◽

Mapk Signaling ◽

Mitogen Activated Protein Kinase ◽

Dependent Manner ◽

Ang Ii ◽

Superoxide Generation ◽

Spontaneous Tone

Arteries from hypertensive animals and humans have increased spontaneous tone. Increased superoxide anion (superoxide) contributes to elevated blood pressure (BP) and spontaneous tone in hypertension. The association between the extracellular signaling-regulated kinase 1/2 (ERK1/2)-mitogen-activated protein kinase (MAPK) signaling pathway and generation of superoxide and spontaneous tone in isolated aorta was studied in angiotensin II (ANG II)-infused hypertensive (HT) rats. Systolic BP, phosphorylation of ERK, aortic superoxide formation, and aortic spontaneous tone were compared in sham normotensive and HT rats. Infusion of ANG II (0.5 mg·kg−1·day−1 for 6 days) significantly elevated the systolic BP ( P < 0.01). The phosphorylation of ERK1/2 vs. total ERK1/2 in thoracic aorta was enhanced, and superoxide was increased in the HT vs. the sham group ( P < 0.01). Spontaneous tone developed in the HT group, but not in the normotensive group. MAPK/ERK1/2 (MEK1/2)-ERK1/2 signaling pathway inhibitors, PD-98059 (10 μmol/l), and U-0126 (10 μmol/l), significantly reduced the phosphorylation of ERK1/2, superoxide generation ( P < 0.01), and spontaneous tone ( P < 0.01) in HT. These findings suggest that ANG II infusion induces the production of superoxide and spontaneous tone and that both are dependent on ERK-MAPK activation. In endothelium-denuded aorta, however, MEK1/2 inhibitors did not inhibit the spontaneous tone, even though they significantly reduced superoxide generation similar to endothelium-intact aorta. These data suggest that inhibition of ERK1/2 signaling pathway, via PD-98059 or U-0126, may regulate spontaneous tone in an endothelium-dependent manner. In conclusion, these findings support the importance of the ERK1/2 signaling pathway in modulating vascular oxidative stress and subsequently mediating spontaneous tone in HT.

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Dependence of endothelium-mediated relaxation on oxygen and metabolism in porcine coronary arteries

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1993.265.1.h299 ◽

1993 ◽

Vol 265 (1) ◽

pp. H299-H306 ◽

Cited By ~ 23

Author(s):

M. Hashimoto ◽

L. A. Close ◽

Y. Ishida ◽

R. J. Paul

Keyword(s):

Substance P ◽

Coronary Arteries ◽

Underlying Mechanism ◽

Slow Phase ◽

Rapid Phase ◽

Hypoxic Conditions ◽

A 23187 ◽

Transient Relaxation ◽

Dose Dependent ◽

Endothelium Dependent Relaxation

Hypoxia has major effects on endothelium-dependent relaxation. To further understand the underlying mechanism(s), we investigated the O2 dependence of the endothelium-dependent relaxations elicited by ionophore A-23187 or agonists substance P (SP) or thrombin (TB) in porcine coronary arteries. A-23187 elicits an endothelium-dependent relaxation of KCl- or U-46619-induced contractures that can be described in terms of a rapid and slow phase. The duration of the relaxation was dose dependent. SP (10 nM) and TB (0.1 U/ml) also elicited endothelium-dependent relaxations that were rapid but transient. Hypoxic conditions (95% N2-5% CO2 instead of 95% O2-5% CO2; PO2 < 1%) abolished the A-23187 rapid phase and the SP and TB transient relaxation but not the A-23187 slow phase. Threshold PO2 for the rapid phase was approximately 35 mmHg. Pretreatment with cyanide (5 mM), to inhibit respiration, or 2-deoxy-D-glucose, to inhibit glycolysis, had little effect. Similarly, propranolol (10 microM) or indomethacin (10 microM) had no effect on the relaxation to A-23187, TB, or SP. In contrast, both NO synthesis inhibitors and ouabain blunted all endothelium-dependent relaxations studied. Our results suggest that the rapid relaxations to A-23187, SP, and TB are sensitive to O2 but not mitochondrial respiration. The slow sustained relaxation induced by A-23187, however, is characterized by a sensitivity to O2 that is distinct from that of the rapid phase, yet is dependent on an intact endothelium and is affected by NO synthesis inhibitors. Thus the endothelium-dependent relaxation to A-23187 is probably mediated by NO, but its sensitivity to O2 suggests that two distinct mechanisms may be involved.

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Mepivacaine-induced contraction involves phosphorylation of extracellular signal-regulated kinase through activation of the lipoxygenase pathway in isolated rat aortic smooth muscle

Canadian Journal of Physiology and Pharmacology ◽

10.1139/cjpp-2012-0197 ◽

2013 ◽

Vol 91 (4) ◽

pp. 285-294 ◽

Cited By ~ 9

Author(s):

Hyo Min Lee ◽

Seong-Ho Ok ◽

Hui-Jin Sung ◽

So Young Eun ◽

Hye Jung Kim ◽

...

Keyword(s):

Smooth Muscle ◽

Nordihydroguaiaretic Acid ◽

Rat Aorta ◽

Dependent Manner ◽

Aortic Smooth Muscle ◽

Extracellular Signal Regulated Kinase ◽

Erk Phosphorylation ◽

Extracellular Signal ◽

Cox 2 ◽

Isolated Rat

Mepivacaine is an aminoamide local anesthetic with an intermediate duration that intrinsically produces vasoconstriction both in vivo and in vitro. This study investigated the arachidonic acid metabolic pathways involved in mepivacaine-induced contraction, and elucidated the associated cellular mechanism with a particular focus on extracellular signal-regulated kinase (ERK) in endothelium-denuded rat aorta. Isolated rat thoracic aortic rings were suspended for isometric tension recording. Cumulative mepivacaine concentration–response curves were generated in the presence or absence of the following inhibitors: quinacrine dihydrochloride, nordihydroguaiaretic acid, phenidone, AA-861, indomethacin, NS-398, SC-560, fluconazole, PD 98059, and verapamil. Mepivacaine-induced ERK phosphorylation, 5-lipoxygenase (5-LOX) expression, and cyclooxygenase (COX)-2 expression in rat aortic smooth muscle cells were detected by Western blot analysis in the presence or absence of inhibitors. Mepivacaine produced tonic contraction in isolated endothelium-denuded rat aorta. Quinacrine dihydrochloride, nordihydroguaiaretic acid, phenidone, AA-861, NS-398, PD 98059, and verapamil attenuated mepivacaine-induced contraction in a concentration-dependent manner. However, fluconazole had no effect on mepivacaine-induced contraction. PD 98059, quinacrine dihydrochloride, nordihydroguaiaretic acid, AA-861, phenidone, and indomethacin attenuated mepivacaine-induced ERK phosphorylation. Mepivacaine upregulated 5-LOX and COX-2 expression. These results suggest that mepivacaine-induced contraction involves ERK activation, which is primarily mediated by the 5-LOX pathway and in part by the COX-2 pathway.

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Smooth muscle cells affect endothelial membrane potential in rat aorta

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1994.267.2.h804 ◽

1994 ◽

Vol 267 (2) ◽

pp. H804-H811 ◽

Cited By ~ 8

Author(s):

S. M. Marchenko ◽

S. O. Sage

Keyword(s):

Methylene Blue ◽

Smooth Muscle ◽

Membrane Potential ◽

Angiotensin Ii ◽

Rat Aorta ◽

No Synthase ◽

Beta Agonist ◽

Patch Clamp Technique ◽

Aortic Smooth Muscle ◽

Ca2 Channels

The effects of vasoconstrictors on membrane potential of endothelium of intact rat aorta were investigated using the patch-clamp technique. Norepinephrine, endothelin (ET)-1, 5-hydroxytryptamine (5-HT), vasopressin, and angiotensin II evoked depolarization and oscillations in membrane potential. The alpha 1-adrenoreceptor agonist phenylephrine (PE), but not the alpha 2-agonist clonidine or the beta-agonist isoproterenol, evoked oscillations. The antagonist of 5-HT2-receptors, ketanserin, inhibited 5-HT-evoked oscillations. ET-3, unlike ET-1, did not evoke oscillations. The antagonists of voltage-operated Ca2+ channels, nifedipine and verapamil, inhibited vasoconstrictor-evoked oscillations, and the Ca2+ channel agonist BAY K 8644 enhanced oscillations. Acetylcholine and sodium nitroprusside inhibited PE-evoked oscillations. The inhibitors of NO synthase, N omega-nitro-L-arginine and NG-methyl-L-arginine, as well as methylene blue, enhanced oscillations. The intima of rat aorta with endothelium was removed from underlying smooth muscle. In this preparation, acetylcholine evoked a response similar to that in the intact vessel, but PE and ET-1 were without effect. These data suggest that vasoconstrictors acting on receptors on aortic smooth muscle evoke a response that is transferred to the endothelium and evokes depolarization and oscillations in endothelial membrane potential.

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