TRPV4 calcium entry channel: a paradigm for gating diversity

2004 ◽  
Vol 286 (2) ◽  
pp. C195-C205 ◽  
Author(s):  
Bernd Nilius ◽  
Joris Vriens ◽  
Jean Prenen ◽  
Guy Droogmans ◽  
Thomas Voets
Keyword(s):  
Cell Swelling ◽  
Epoxyeicosatrienoic Acids ◽  
Founding Member ◽  
Sequence Identity ◽  
Vanilloid Receptor 1 ◽  
Hypotonic Cell Swelling ◽  
Chemical Stimuli ◽  
Physical And Chemical ◽  
Cytochrome P 450 ◽  
Endogenous Substances

The vanilloid receptor-1 (VR1, now TRPV1) was the founding member of a subgroup of cation channels within the TRP family. The TRPV subgroup contains six mammalian members, which all function as Ca2+ entry channels gated by a variety of physical and chemical stimuli. TRPV4, which displays 45% sequence identity with TRPV1, is characterized by a surprising gating promiscuity: it is activated by hypotonic cell swelling, heat, synthetic 4α-phorbols, and several endogenous substances including arachidonic acid (AA), the endocannabinoids anandamide and 2-AG, and cytochrome P-450 metabolites of AA, such as epoxyeicosatrienoic acids. This review summarizes data on TRPV4 as a paradigm of gating diversity in this subfamily of Ca2+ entry channels.

Role of PGI2 and epoxyeicosatrienoic acids in relaxation of bovine coronary arteries to arachidonic acid

1993 ◽  
Vol 264 (2) ◽  
pp. H327-H335 ◽  
Author(s):  
M. Rosolowsky ◽  
W. B. Campbell
Keyword(s):  
Arachidonic Acid ◽  
Coronary Arteries ◽  
Vascular Tone ◽  
Epoxyeicosatrienoic Acids ◽  
Lipoxygenase Inhibitor ◽  
Physiological Processes ◽  
Coronary Vascular Tone ◽  
Cytochrome P 450 ◽  
Endothelium Dependent Relaxation

Metabolites of arachidonic acid regulate several physiological processes, including vascular tone. The purpose of this study was to determine which metabolites of arachidonic acid are produced by bovine coronary arteries and which may regulate coronary vascular tone. Arachidonic acid induced a concentration-related, endothelium-dependent relaxation [one-half maximum effective concentration (EC50) of 2 x 10(-7) M and a maximal relaxation of 91 +/- 2% at 10(-5) M] of bovine coronary arteries that were contracted with U-46619, a thromboxane mimetic. The concentration of 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha), a metabolite of prostaglandin I2 (PGI2), increased from 82 +/- 6 to 328 +/- 24 pg/ml with arachidonic acid (10(-5) M). Treatment with the cyclooxygenase inhibitor indomethacin attenuated arachidonic acid-induced relaxations by approximately 50% and blocked the synthesis of 6-keto-PGF1 alpha. PGI2 caused a concentration-related relaxation (EC50 of 10(-8) M and a maximal relaxation of 125 +/- 11% at 10(-7) M). BW755C, a cyclooxygenase and lipoxygenase inhibitor, inhibited arachidonic acid-induced relaxation to the same extent as indomethacin. When vessels were treated with both indomethacin and BW755C, the inhibition of relaxation was the same as either inhibitor alone. SKF 525a, a cytochrome P-450 inhibitor, reduced arachidonic acid-induced relaxation by approximately 50%. When SKF 525a was given in combination with indomethacin, the relaxation by arachidonic acid was almost completely inhibited. SKF 525a inhibited the synthesis of epoxyeicosatrienoic acids (EETs).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Stimuli that induce a yeast heat shock gene fused to beta-galactosidase.

1984 ◽  
Vol 4 (12) ◽  
pp. 2573-2579 ◽  
Author(s):  
C Brazzell ◽  
T D Ingolia
Keyword(s):  
Heat Shock ◽  
Heat Shock Gene ◽  
Enzyme Assays ◽  
Lacz Gene ◽  
Directed Synthesis ◽  
Shock Gene ◽  
Chemical Stimuli ◽  
Physical And Chemical ◽  
Beta Galactosidase

Saccharomyces cerevisiae contain a multigene family related to the Drosophila heat shock gene hsp70. Two members of this family, YG100 and YG101, have been previously characterized (Ingolia et al., Mol. Cell. Biol. 2:1388-1398, 1982), and only YG100 was found to have elevated levels of transcription after heat shock. The yeast hsp70 genes contained on YG100 and YG101 were truncated and fused to the Escherichia coli lacZ gene contained on pMC1587 (Casadaban et al., Methods Enzymol. 100:283-308, 1983). The resulting plasmids directed synthesis of the beta-galactosidase gene as measured by in vitro enzyme assays and by colorimetric assays on plates. The expression level from the YG101 gene was constant under all the conditions tested, whereas expression driven by the YG100 gene could be induced over 50-fold. Other stimuli besides heat, including recovery from anoxia and high cell density, were found to strongly induce YG100 gene expression. Most physical and chemical stimuli tested, including UV irradiation, zymolyase treatment, and ethanol, did not stimulate expression of this heat shock gene.

EETs relax airway smooth muscle via an EpDHF effect: BKCa channel activation and hyperpolarization

2001 ◽  
Vol 280 (5) ◽  
pp. L965-L973 ◽  
Author(s):  
Catherine Benoit ◽  
Barbara Renaudon ◽  
Dany Salvail ◽  
Eric Rousseau
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Molecular Mechanisms ◽  
Muscle Tone ◽  
Muscle Relaxation ◽  
Smooth Muscle Relaxation ◽  
Epoxyeicosatrienoic Acids ◽  
Bkca Channel ◽  
Channel Activity ◽  
Cytochrome P 450

Epoxyeicosatrienoic acids (EETs) are produced from arachidonic acid via the cytochrome P-450 epoxygenase pathway. EETs are able to modulate smooth muscle tone by increasing K+ conductance, hence generating hyperpolarization of the tissues. However, the molecular mechanisms by which EETs induce smooth muscle relaxation are not fully understood. In the present study, the effects of EETs on airway smooth muscle (ASM) were investigated using three electrophysiological techniques. 8,9-EET and 14,15-EET induced concentration-dependent relaxations of the ASM precontracted with a muscarinc agonist (carbamylcholine chloride), and these relaxations were partly inhibited by 10 nM iberiotoxin (IbTX), a specific large-conductance Ca2+-activated K+ (BKCa) channel blocker. Moreover, 3 μM 8,9- or 14,15-EET induced hyperpolarizations of −12 ± 3.5 and −16 ± 3 mV, with EC50 values of 0.13 and 0.14 μM, respectively, which were either reversed or blocked on addition of 10 nM IbTX. These results indicate that BKCa channels are involved in hyperpolarization and participate in the relaxation of ASM. In addition, complementary experiments demonstrated that 8,9- and 14,15-EET activate reconstituted BKCa channels at low free Ca2+ concentrations without affecting their unitary conductance. These increases in channel activity were IbTX sensitive and correlated well with the IbTX-sensitive hyperpolarization and relaxation of ASM. Together these results support the view that, in ASM, the EETs act through an epithelium-derived hyperpolarizing factorlike effect.

Decreased epoxygenase and increased epoxide hydrolase expression in the mesenteric artery of obese Zucker rats

2005 ◽  
Vol 288 (1) ◽  
pp. R188-R196 ◽  
Author(s):  
Xueying Zhao ◽  
Aparajita Dey ◽  
Olga P. Romanko ◽  
David W. Stepp ◽  
Mong-Heng Wang ◽  
...  
Keyword(s):  
Mesenteric Artery ◽  
Epoxide Hydrolase ◽  
Soluble Epoxide Hydrolase ◽  
Mesenteric Arteries ◽  
Zucker Rats ◽  
Epoxyeicosatrienoic Acids ◽  
Obese Zucker Rat ◽  
Protein Expressions ◽  
Obese Zucker Rats ◽  
Cytochrome P 450

Previous studies suggest that epoxyeicosatrienoic acids (EETs) are vasodilators of the mesenteric artery; however, the production and regulation of EETs in the mesenteric artery remain unclear. The present study was designed 1) to determine which epoxygenase isoform may contribute to formation of EETs in mesenteric arteries and 2) to determine the regulation of mesenteric artery cytochrome P-450 (CYP) enzymes in obese Zucker rats. Microvessels were incubated with arachidonic acid, and CYP enzyme activity was determined. Mesenteric arteries demonstrate detectable epoxygenase and hydroxylase activities. Next, protein and mRNA expressions were determined in microvessels. Although renal microvessels express CYP2C23 mRNA and protein, mesenteric arteries lacked CYP2C23 expression. CYP2C11 and CYP2J mRNA and protein were expressed in mesenteric arteries and renal microvessels. In addition, mesenteric artery protein expression was evaluated in lean and obese Zucker rats. Compared with lean Zucker rats, mesenteric arterial CYP2C11 and CYP2J proteins were decreased by 38 and 43%, respectively, in obese Zucker rats. In contrast, soluble epoxide hydrolase mRNA and protein expressions were significantly increased in obese Zucker rat mesenteric arteries. In addition, nitric oxide-independent dilation evoked by acetylcholine was significantly attenuated in mesenteric arteries of obese Zucker rats. These data suggest that the main epoxygenase isoforms expressed in mesenteric arteries are different from those expressed in renal microvessels and that decreased epoxygenases and increased soluble epoxide hydrolase are associated with impaired mesenteric artery dilator function in obese Zucker rats.

Cytochrome P-450 epoxygenase products contribute to attenuated vasoconstriction after chronic hypoxia

2003 ◽  
Vol 285 (1) ◽  
pp. H127-H136 ◽  
Author(s):  
Scott Earley ◽  
Andrzej Pastuszyn ◽  
Benjimen R. Walker
Keyword(s):  
Chronic Hypoxia ◽  
Barometric Pressure ◽  
Mesenteric Arteries ◽  
Resting Membrane Potential ◽  
Epoxyeicosatrienoic Acids ◽  
Resistance Arteries ◽  
Protein Levels ◽  
Acid Metabolites ◽  
Channel Dependent ◽  
Cytochrome P 450

The systemic vasculature exhibits attenuated vasoconstriction following chronic hypoxia (CH) that is associated with endothelium-dependent vascular smooth muscle (VSM) cell hyperpolarization. We hypothesized that increased production of arachidonic acid metabolites such as the cyclooxygenase product prostacyclin or cytochrome P-450 (CYP) epoxygenase-derived epoxyeicosatrienoic acids (EETs) contributes to VSM cell hyperpolarization following CH. VSM cell resting membrane potential ( Em) was measured in superior mesenteric artery strips isolated from rats with control barometric pressure (Pb, ≅630 Torr) and CH (Pb, 380 Torr for 48 h). VSM cell Em was normalized between groups following administration of the CYP inhibitors 17-octadecynoic acid and SKF-525A. VSM cell hyperpolarization after CH was not altered by cyclooxygenase inhibition, whereas the selective CYP2C9 inhibitor sulfaphenazole normalized VSM cell Em between groups. Iberiotoxin also normalized VSM cell Em, which suggests that large-conductance, Ca2+-activated K+ (BKCa) channel activity is increased after CH. Sulfaphenazole administration restored phenylephrine-induced and myogenic vasoconstriction and Ca2+ responses of mesenteric resistance arteries isolated from CH rats to control levels. Western blot experiments demonstrated that CYP2C9 protein levels were greater in mesenteric arteries from CH rats. In addition, 11,12-EET levels were elevated in endothelial cells from CH rats compared with controls. We conclude that enhanced CYP2C9 expression and 11,12-EET production following CH contributes to BKCa channel-dependent VSM cell hyperpolarization and attenuated vasoreactivity.

Effects of Benzydamine Eye Drops on the Rabbit's Eye Reaction to Surgical, Physical, and Chemical Stimuli

1989 ◽  
Vol 5 (1) ◽  
pp. 71-80 ◽  
Author(s):  
L. TOMAZZOLI ◽  
A. BONORA ◽  
M.R. LUPARINI ◽  
L. DURANDO ◽  
M.G. CIARNIELLO ◽  
...  
Keyword(s):  
Eye Drops ◽  
Chemical Stimuli ◽  
Physical And Chemical

Fluorescent HPLC assay for 20-HETE and other P-450 metabolites of arachidonic acid

2000 ◽  
Vol 279 (2) ◽  
pp. H863-H871 ◽  
Author(s):  
Kristopher G. Maier ◽  
Lisa Henderson ◽  
Jayashree Narayanan ◽  
Magdalena Alonso-Galicia ◽  
John R. Falck ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Interstitial Fluid ◽  
Internal Standard ◽  
Dienoic Acid ◽  
Renal Tissue ◽  
Gas Chromatography Mass Spectrometry ◽  
Epoxyeicosatrienoic Acids ◽  
Hplc Assay ◽  
Standard Curve ◽  
Cytochrome P 450

This study describes a fluorescent HPLC assay for measuring 20-hydroxyeicosatetraenoic acid (20-HETE) and other cytochrome P-450 metabolites of arachidonic acid in urine, tissue, and interstitial fluid. An internal standard, 20-hydroxyeicosa-6( Z),15( Z)-dienoic acid, was added to samples, and the lipids were extracted and labeled with 2-(2,3-naphthalimino)ethyl trifluoromethanesulfonate. P-450 metabolites were separated on a C18 reverse-phase HPLC column. Coelution and gas chromatography-mass spectrometry studies confirmed the identity of the 20-HETE peak. The 20-HETE peak can be separated from those for dihydroxyeicosatrienoic acids, other HETEs, and epoxyeicosatrienoic acids. Known amounts of 20-HETE were used to generate a standard curve (range 1–10 ng, r 2 = 0.98). Recovery of 20-HETE from urine averaged 95%, and the intra-assay variation was <5%. Levels of 20-HETE were measured in 100 μl of urine and renal interstitial fluid or 0.1 mg of renal tissue. The assay was evaluated by studying the effects of 1-aminobenzotriazole (ABT) on the excretion of 20-HETE in rats. ABT reduced excretion of 20-HETE by >65% and inhibited the formation of 20-HETE by renal microsomes. The availability of this assay should facilitate work in this field.

Ca2+ uptake in GH3 cells during hypotonic swelling: the sensory role of stretch-activated ion channels

1996 ◽  
Vol 270 (6) ◽  
pp. C1790-C1798 ◽  
Author(s):  
Y. Chen ◽  
S. M. Simasko ◽  
J. Niggel ◽  
W. J. Sigurdson ◽  
F. Sachs
Keyword(s):  
Volume Regulation ◽  
Cell Swelling ◽  
Gh3 Cells ◽  
Membrane Tension ◽  
Hypotonic Cell Swelling ◽  
Stretch Activated Channels ◽  
Ca2 Channels ◽  
Hypotonic Swelling ◽  
Volume Decrease

Hypotonic cell swelling triggers an increase in intracellular Ca2+ concentration that is deemed responsible for the subsequent regulated volume decrease in many cells. To understand the mechanisms underlying this increase, we have studied the Ca2+ sources that contribute to hypotonic cell swelling-induced Ca2+ increase (HICI) in GH3 cells. Fura 2 fluorescence of cell populations revealed that extracellular, but not intracellular, stores of Ca2+ were required. HICI was abolished by nifedipine, a blocker of L-type Ca2+ channels, and Gd3+, a nonspecific blocker of stretch-activated channels (SACs), suggesting two components for the Ca2+ membrane pathway: L-type Ca2+ channels and SACs. Using HICI as an assay, we found that venom from the spider Grammostola spatulata could block HICI without blocking L-type Ca2+ channels. The venom did, however, block SAC activity. This suggests that Ca(2+)-permeable SACs, rather than L-type Ca2+ channels, are the sensing elements for HICI. These results support the model for volume regulation in which SACs, activated by an increase of the membrane tension during hypotonic cell swelling, trigger HICI, leading to a volume decrease.

Cerebral microvascular endothelial cell tube formation: role of astrocytic epoxyeicosatrienoic acid release

2000 ◽  
Vol 278 (4) ◽  
pp. H1163-H1167 ◽  
Author(s):  
Diane H. Munzenmaier ◽  
David R. Harder
Keyword(s):  
Thymidine Incorporation ◽  
Tube Formation ◽  
Microvascular Endothelial Cell ◽  
Epoxyeicosatrienoic Acids ◽  
Epoxyeicosatrienoic Acid ◽  
Acid Release ◽  
Microvascular Endothelial ◽  
Cytochrome P 450 ◽  
The Brain

Cerebral microvascular endothelial cells (CMVEC) form tubes when cocultured with astrocytes (AS). Therefore, it appears that AS may be important in mediating angiogenesis in the brain. We hypothesized that AS modulate CMVEC tube formation by releasing a soluble factor. Thymidine incorporation in cultured CMVEC increased 305% when incubated with 50% conditioned AS medium for 24 h [control: 52,755 ± 4,838 counts per minute (cpm) per well, conditioned 161,082 ± 12,099 cpm/well, n = 8]. Because our laboratory has previously shown that AS can produce epoxyeicosatrienoic acids (EETs), which are known mitogens, we investigated whether release of EETs by AS is responsible for tube formation in the CMVEC-AS coculture. AS were seeded on Lab-Tek slides, CMVEC were seeded on the AS the next day, and cultures were allowed to progress for another 5 days with and without cytochrome P-450 epoxygenase blockade by 17-octadecynoic acid (17-ODYA). Tube formation in cocultures receiving 17-ODYA was significantly inhibited compared with control (93.8%). These data suggest that tube formation requires the release of EETs by AS.

Sign in / Sign up

Export Citation Format

Share Document