Abstract 932: Temporal Changes In The Contribution Of Protein Kinase C Isoforms To Myogenic Constriction In Rat Posterior Cerebral Arteries

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Toshihide Kashihara ◽  
Koichi Nakayama ◽  
Tomohisa Ishikawa
Keyword(s):  
Initial Phase ◽  
Cerebral Arteries ◽  
Ruthenium Red ◽  
Intraluminal Pressure ◽  
Myogenic Tone ◽  
Kinase C ◽  
Pkc Isoforms ◽  
Pkc Inhibitors ◽  
Protein Kinase C Isoforms

Background Cerebral arteries respond to an increase in intraluminal pressure with vasoconstriction, being referred to as myogenic tone. A number of studies have postulated the mechanisms involved in the development of myogenic tone; however, less information is available about how myogenic tone is maintained. The present study thus investigated the mechanisms underlying sustained myogenic constriction in isolated rat posterior cerebral arteries. Methods and Results Long-term elevation of intraluminal pressure from 5 to 60 mmHg for 1 hr caused sustained constriction and [Ca 2+ ] i elevation. In the presence of rottlerin, a PKCδ inhibitor, the pressure-induced constriction and [Ca 2+ ] i elevation were gradually declined, and nearly abolished at the end of the 1-hr stimulation (sustained phase). In contrast, Gö 6976, a cPKC inhibitor, significantly inhibited the constriction for up to 5 min after the start of stimulation (initial phase), but had no effects on the [Ca 2+ ] i elevation. The pressure stimulation induced small [Ca 2+ ] i elevation even in the presence of nicaripine. Ruthenium red (RuR), a TRPV inhibitor, significantly inhibited the nicardipine-resistant [Ca 2+ ] i elevation in the initial phase. However, slowly developing [Ca 2+ ] i elevation was still observed in the sustained phase. In contrast, rottlerin had little effect on the initial phase, but significantly inhibited the sustained one. Moreover, the combination of RuR and rottlerin nearly abolished the nicardipine-resistant [Ca 2+ ] i elevation. PKCα, γ, δ, and ε, but not PKCβ, were detected by immunohistochemisty in smooth muscle cells of rat posterior cerebral arteries. Conclusions PKC isoforms have different roles in the development and maintain of the myogenic constriction in rat posterior cerebral arteries: cPKC (α and/or γ) mediates Ca 2+ sensitization in the initial phase, whereas PKCδ mediates [Ca 2+ ] i elevation via the activation of RuR-resistant cation channels in the sustained phase. Table. Effects of PKC inhibitors on pressure-induced constriction and [Ca 2+ ] i elevation

Low [Mg2+]o induces contraction and [Ca2+]i rises in cerebral arteries: roles of Ca2+, PKC, and PI3

2000 ◽  
Vol 279 (6) ◽  
pp. H2898-H2907 ◽  
Author(s):  
Zhi-Wei Yang ◽  
Jun Wang ◽  
Tao Zheng ◽  
Bella T. Altura ◽  
Burton M. Altura
Keyword(s):  
Cerebral Arteries ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Voltage Gated ◽  
Selective Antagonist ◽  
Kinase C ◽  
Pkc Isoforms ◽  
Intracellular Ca ◽  
Basilar Arteries ◽  
Specific Antagonist

Removal of extracellular Ca2+ concentration ([Ca2+]o) and pretreatment of canine basilar arterial rings with either an antagonist of voltage-gated Ca2+ channels (verapamil), a selective antagonist of the sarcoplasmic reticulum Ca2+ pump [thapsigargin (TSG)], caffeine plus a specific antagonist of ryanodine-sensitive Ca2+ release (ryanodine), or ad- myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3]- mediated Ca2+ release antagonist (heparin) markedly attenuates low extracellular Mg2+ concentration ([Mg2+]o)-induced contractions. Low [Mg2+]o-induced contractions are significantly inhibited by pretreatment of the vessels with Gö-6976 [a protein kinase C-α (PKC-α)- and PKC-βI-selective antagonist], bisindolylmaleimide I (Bis, a specific antagonist of PKC), and wortmannin or LY-294002 [selective antagonists of phosphatidylinositol-3 kinases (PI3Ks)]. These antagonists were also found to relax arterial contractions induced by low [Mg2+]o in a concentration-dependent manner. The absence of [Ca2+]o and preincubation of the cells with verapamil, TSG, heparin, or caffeine plus ryanodine markedly attenuates the transient and sustained elevations in the intracellular Ca2+ concentration ([Ca2+]i) induced by low-[Mg2+]o medium. Low [Mg2+]o-produced increases in [Ca2+]i are also suppressed markedly in the presence of Gö-6976, Bis, wortmannin, or LY-294002. The present study suggests that both Ca2+ influx through voltage-gated Ca2+ channels and Ca2+ release from intracellular stores [both Ins(1,4,5)P3sensitive and ryanodine sensitive] play important roles in low-[Mg2+]o medium-induced contractions of isolated canine basilar arteries. Such contractions are clearly associated with activation of PKC isoforms and PI3Ks.

scholarly journals Increased pressure-induced tone in rat parenchymal arterioles vs. middle cerebral arteries: role of ion channels and calcium sensitivity

2014 ◽  
Vol 117 (1) ◽  
pp. 53-59 ◽  
Author(s):  
Marilyn J. Cipolla ◽  
Julie Sweet ◽  
Siu-Lung Chan ◽  
Matthew J. Tavares ◽  
Natalia Gokina ◽  
...  
Keyword(s):  
Ion Channel ◽  
Small Vessel Disease ◽  
Cerebral Arteries ◽  
Calcium Sensitivity ◽  
Cytosolic Calcium ◽  
Intraluminal Pressure ◽  
Myogenic Tone ◽  
Contractile Apparatus ◽  
Pial Arteries ◽  
Middle Cerebral Arteries

Brain parenchymal arterioles (PAs) are high-resistance vessels that branch off pial arteries and perfuse the brain parenchyma. PAs are the target of cerebral small vessel disease and have been shown to have greater pressure-induced tone at lower pressures than pial arteries. We investigated mechanisms by which brain PAs have increased myogenic tone compared with middle cerebral arteries (MCAs), focusing on differences in vascular smooth muscle (VSM) calcium and ion channel function. The amount of myogenic tone and VSM calcium was measured using Fura 2 in isolated and pressurized PAs and MCAs. Increases in intraluminal pressure caused larger increases in tone and cytosolic calcium in PAs compared with MCAs. At 50 mmHg, myogenic tone was 37 ± 5% for PAs vs. 6.5 ± 4% for MCAs ( P < 0.01), and VSM calcium was 200 ± 20 nmol/l in PAs vs. 104 ± 15 nmol/l in MCAs ( P < 0.01). In vessels permeabilized with Staphylococcus aureus α-toxin, PAs were not more sensitive to calcium, suggesting calcium sensitization was not at the level of the contractile apparatus. PAs were 30-fold more sensitive to the voltage-dependent calcium channel (VDCC) inhibitor nifedipine than MCAs (EC50 for PAs was 3.5 ± 0.4 vs. 82.1 ± 2.1 nmol/l for MCAs; P < 0.01); however, electrophysiological properties of the VDCC were not different in VSM. PAs had little to no response to the calcium-activated potassium channel inhibitor iberiotoxin, whereas MCAs constricted ∼15%. Thus increased myogenic tone in PAs appears related to differences in ion channel activity that promotes VSM membrane depolarization but not to a direct sensitization of the contractile apparatus to calcium.

Impaired pressure-induced constriction in mouse middle cerebral arteries of ASIC2 knockout mice

2008 ◽  
Vol 294 (4) ◽  
pp. H1793-H1803 ◽  
Author(s):  
Kimberly P. Gannon ◽  
Lauren G. VanLandingham ◽  
Nikki L. Jernigan ◽  
Samira C. Grifoni ◽  
Gina Hamilton ◽  
...  
Keyword(s):  
Ion Channel ◽  
Sensory Neurons ◽  
Knockout Mice ◽  
Cerebral Arteries ◽  
Normal Pressure ◽  
Intraluminal Pressure ◽  
Myogenic Tone ◽  
Wild Type ◽  
Middle Cerebral Arteries

Recent studies from our laboratory demonstrated the importance of mechanosensitive epithelial Na+ channel (ENaC) proteins in pressure-induced constriction in renal and cerebral arteries. ENaC proteins are closely related to acid-sensing ion channel 2 (ASIC2), a protein known to be required for normal mechanotransduction in certain sensory neurons. However, the role of the ASIC2 protein in pressure-induced constriction has never been addressed. The goal of the current study was to investigate the role of ASIC2 proteins in pressure-induced, or myogenic, constriction in the mouse middle cerebral arteries (MCAs) from ASIC2 wild-type (+/+), heterozygous (+/−), and null (−/−) mice. Constrictor responses to KCl (20–80 mM) and phenylephrine (10−7–10−4 M) were not different among groups. However, vasoconstrictor responses to increases in intraluminal pressure (15–90 mmHg) were impaired in MCAs from ASIC2−/− and +/− mice. At 60 and 90 mmHg, MCAs from ASIC2+/+ mice generated 13.7 ± 2.1% and 15.8 ± 2.0% tone and ASIC2−/− mice generated 7.4 ± 2.8% and 12.5 ± 2.4% tone, respectively. Surprisingly, MCAs from ASIC2+/− mice generated 1.2 ± 2.2% and 3.9 ± 1.8% tone at 60 and 90 mmHg. The reason underlying the total loss of myogenic tone in the ASIC2+/− is not clear, although the loss of mechanosensitive β- and γ-ENaC proteins may be a contributing factor. These results demonstrate that normal ASIC2 expression is required for normal pressure-induced constriction in the MCA. Furthermore, ASIC2 may be involved in establishing the basal level of myogenic tone.

scholarly journals Distribution of Protein Kinase C Isoforms after Infection of Macrophages with Leishmania major

1998 ◽  
Vol 66 (4) ◽  
pp. 1795-1799 ◽  
Author(s):  
Sabine Pingel ◽  
Zhi-En Wang ◽  
Richard M. Locksley
Keyword(s):  
Gene Expression ◽  
Bone Marrow ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Leishmania Major ◽  
Murine Bone Marrow ◽  
Kinase C ◽  
Pkc Isoforms ◽  
Protein Kinase C Isoforms

ABSTRACT We characterized the effects of Leishmania infection on activation-induced translocation of protein kinase C (PKC) isoforms in murine bone marrow-derived macrophages. Although PKC-dependent gene expression was attenuated by infection, the distribution and translocation of PKC isoforms were unaffected. However, subsequent dissociation from membranes was substantially delayed for some isoforms, particularly PKCβ.

Influence of endothelin receptor antagonists on myocardial protein kinase C isoforms in uraemic cardiomyopathy

2002 ◽  
Vol 103 (s2002) ◽  
pp. 276S-279S ◽  
Author(s):  
Sabine C. WOLF ◽  
Thorsten AMEND ◽  
Teut RISLER ◽  
Kerstin AMANN ◽  
Bernhard R. BREHM
Keyword(s):  
Blood Pressure ◽  
Renal Failure ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Receptor Antagonist ◽  
Kinase C ◽  
Pkc Isoforms ◽  
Eta Receptor ◽  
Eta Receptor Antagonist ◽  
Protein Kinase C Isoforms

Increased endothelin-1 (ET-1) levels were found in patients with chronic renal failure and these correlate with the severity of renal failure. Increased mortality due to cardiovascular problems is observed in patients with elevated ET-1 concentrations. The aim of this study was to find out the influence of ET-1 and ET receptor antagonists on myocardial protein kinase C (PKC) regulation in uraemic cardiomyopathy. Male rats were subtotally nephrectomized and treated with an ETA-receptor antagonist (30mg·kg-1·day-1, LU302146) or an ETAB-receptor antagonist (30mg·kg-1·day-1, LU302872) for 12 weeks. One group was left untreated (SNX) and one group was sham-operated (sham). Systolic blood pressure, myocardial weight and the changes of the protein kinase C isoforms in the heart were determined. PKC isoforms α and δ were investigated by Western blot analysis using specific antibodies. In the SNX group, systolic blood pressure rose to 154±5mmHg after 12 weeks. The ETA receptor antagonist prevented this increase in blood pressure, but ETAB antagonism did not. Left ventricular weight increased in SNX; this increase was inhibited by the ETA receptor antagonist. In comparison with the sham group, PKC isoform α increased by 19% in SNX animals. When the SNX animals were treated with ETA or ETAB antagonists, PKC isoform α levels decreased by 31%. PKC isoform δ levels decreased by 35% in SNX animals. Treatment with both ETA or ETAB antagonists increased PKC isoform δ levels to normal. In the myocardium of uraemic rats PKC isoforms are differentially regulated with an increase in α isoform but a decrease in δ isoform. ET receptor blockers normalize these PKC isoforms.

Protein kinase C regulates vascular myogenic tone through activation of TRPM4

2007 ◽  
Vol 292 (6) ◽  
pp. H2613-H2622 ◽  
Author(s):  
Scott Earley ◽  
Stephen V. Straub ◽  
Joseph E. Brayden
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Antisense Oligonucleotides ◽  
Cerebral Arteries ◽  
Myogenic Tone ◽  
Kinase C ◽  
Intracellular Ca ◽  
Cell Depolarization ◽  
Stimulation Of

Myogenic vasoconstriction results from pressure-induced vascular smooth muscle cell depolarization and Ca2+ influx via voltage-dependent Ca2+ channels, a process that is significantly attenuated by inhibition of protein kinase C (PKC). It was recently reported that the melastatin transient receptor potential (TRP) channel TRPM4 is a critical mediator of pressure-induced smooth muscle depolarization and constriction in cerebral arteries. Interestingly, PKC activity enhances the activation of cloned TRPM4 channels expressed in cultured cells by increasing sensitivity of the channel to intracellular Ca2+. Thus we postulated that PKC-dependent activation of TRPM4 might be a critical mediator of vascular myogenic tone. We report here that PKC inhibition attenuated pressure-induced constriction of cerebral vessels and that stimulation of PKC activity with phorbol 12-myristate 13-acetate (PMA) enhanced the development of myogenic tone. In freshly isolated cerebral artery myocytes, we identified a Ca2+-dependent, rapidly inactivating, outwardly rectifying, iberiotoxin-insensitive cation current with properties similar to those of expressed TRPM4 channels. Stimulation of PKC activity with PMA increased the intracellular Ca2+ sensitivity of this current in vascular smooth muscle cells. To validate TRPM4 as a target of PKC regulation, antisense technology was used to suppress TRPM4 expression in isolated cerebral arteries. Under these conditions, the magnitude of TRPM4-like currents was diminished in cells from arteries treated with antisense oligonucleotides compared with controls, identifying TRPM4 as the molecular entity responsible for the PKC-activated current. Furthermore, the extent of PKC-induced smooth muscle cell depolarization and vasoconstriction was significantly decreased in arteries treated with TRPM4 antisense oligonucleotides compared with controls. We conclude that PKC-dependent regulation of TRPM4 activity contributes to the control of cerebral artery myogenic tone.

scholarly journals Impaired membrane translocation of thrombin stimulated PKC epsilon by high glucose

1998 ◽  
Vol 157 (2) ◽  
pp. R7-10
Author(s):  
G Reining ◽  
S Baumgartner-Parzer ◽  
W Waldhausl
Keyword(s):  
Umbilical Vein ◽  
Area Under The Curve ◽  
Resting Cells ◽  
Kinase C ◽  
Pkc Epsilon ◽  
Pkc Isoforms ◽  
Membrane Bound ◽  
Pkc Alpha ◽  
Umbilical Vein Endothelial Cells

Hyperglycaemia is known to cause endothelial dysfunction and to promote diabetic angiopathy. Therefore, this study was designed to evaluate the effect of long term incubation (16 +/- 1 days) in 30 mM vs 5 mM glucose on ligand induced translocation of protein kinase C (PKC) in paired cultures of individual isolates of human umbilical vein endothelial cells (HUVECs). Cells were stimulated with increasing concentrations of thrombin (0.01, 0.1, 1, 10 and 100 nM) for 30 seconds in the presence of 5 mM and 30 mM glucose, respectively, and analyzed by immunoblotting for PKC-isoforms alpha and epsilon. Stimulation by thrombin of confluent cultures displayed a concentration dependent rise in membrane bound PKC alpha and epsilon. Translocation of PKC alpha by thrombin remained unaffected by high versus normal ambient glucose, whereas translocation of PKC epsilon in cells grown in 30mM glucose was reduced at maximal thrombin concentrations (area under the curve, AUC: 90.4 +/- 7% of control cells; p < 0.008; n = 6) versus control cultures kept in 5mM glucose. In the identical isolates translocation of PKC epsilon was not reduced by 30 mM mannitol used as osmotic control. No change was induced by long term incubation of resting cells with 30 mM vs 5 mM glucose as to total and membrane bound PKC alpha or PKC epsilon. The obtained data suggest modulation by 30 mM glucose of ligand induced PKC translocation in an isoform specific manner, whereas subcellular distribution of PKC isoforms in the absence of thrombin stimulation remains unaffected by 30 mM glucose.

Importance of PKC and PI3Ks in ethanol-induced contraction of cerebral arterial smooth muscle

2001 ◽  
Vol 280 (5) ◽  
pp. H2144-H2152 ◽  
Author(s):  
Zhi-Wei Yang ◽  
Jun Wang ◽  
Tao Zheng ◽  
Bella T. Altura ◽  
Burton M. Altura
Keyword(s):  
Smooth Muscle ◽  
Intracellular Signaling ◽  
Cerebral Arteries ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Kinase C ◽  
Pkc Isoforms ◽  
Intracellular Ca ◽  
Basilar Arteries ◽  
Specific Antagonist

We investigated the relationships of two potential intracellular signaling pathways, protein kinase C (PKC) and phosphatidylinositol 3-kinases (PI3Ks), to ethanol-induced contractions in cerebral arteries. Ethanol (20–200 mM) induces concentration-dependent constriction in isolated canine basilar arteries that is inhibited in a concentration-dependent manner by pretreatment of these vessels with 10−9–10−3 M Gö-6976 (an antagonist selective for PKC-α and PKC-βI), 10−10–10−4 M bisindolylmaleimide I (a specific antagonist of PKC), and 10−10–10−4 M wortmannin or 10−8–10−2 M LY-294002 (selective antagonists of PI3Ks). Ethanol-induced increases in intracellular Ca2+ concentration (from ∼100 to ∼500 nM) in canine basilar smooth muscle cells are also suppressed markedly (∼20–70%) in the presence of a similar concentration range of Gö-6976, bisindolymaleimide I, wortmannin, or LY-294002. This study suggests that activation of PKC isoforms and PI3Ks appears to be an important signaling pathway in ethanol-induced vasoconstriction of cerebral blood vessels.

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