scholarly journals Mitochondria regulate TRPV4 mediated release of ATP

2021 ◽  
Author(s):  
Xun Zhang ◽  
Matthew Lee ◽  
Charlotte Buckley ◽  
Calum Wilson ◽  
John McCarron
Keyword(s):  
Purinergic Receptors ◽  
Experimental Approach ◽  
Channel Blocker ◽  
Atp Release ◽  
Cyclopiazonic Acid ◽  
Inositol Triphosphate ◽  
Resistance Arteries ◽  
Synthase Inhibitor ◽  
Trpv4 Channel

Background and Purpose Ca influx via TRPV4 triggers Ca release from the IP-sensitive internal store to generate repetitive oscillations. While mitochondria are acknowledged regulators of IP-mediated Ca release, how TRPV4-mediated Ca signals are regulated by mitochondria is unknown. We show that depolarised mitochondria switch TRPV4 signalling from relying on Ca-induced Ca release at IP receptors, to being independent of Ca influx and instead mediated by ATP release via pannexins. Experimental Approach TRPV4 evoked Ca signals were individually examined in hundreds of cells in the endothelium of rat mesenteric resistance arteries using the indicator Cal520. Key ResultsTRPV4 activation with GSK1016790A(GSK) generated repetitive Ca oscillations that required Ca influx. However, when the mitochondrial membrane potential was depolarised, by the uncoupler CCCP or complex I inhibitor rotenone, TRPV4 activation generated large propagating, multicellular, Ca waves in the absence of external Ca. The ATP synthase inhibitor oligomycin did not potentiate TRPV4 mediated Ca signals. GSK-evoked Ca waves, when mitochondria were depolarised, were blocked by the TRPV4 channel blocker HC067047, the SERCA inhibitor cyclopiazonic acid, the phospholipase C (PLC) blocker U73122 and the inositol triphosphate receptor (IP R) blocker caffeine. The Ca waves were also inhibited by the extracellular ATP blockers suramin and apyrase and the pannexin blocker probenecid. Conclusion and Implications These results highlight a previously unknown role of mitochondria in shaping TRPV4 mediated Ca signalling by facilitating ATP release. When mitochondria are depolarised, TRPV4-mediated release of ATP via pannexin channels activates plasma membrane purinergic receptors to trigger IP evoked Ca release.

scholarly journals Mechanisms of ATP release in pain: role of pannexin and connexin channels

2021 ◽  
Author(s):  
Manuel F. Muñoz ◽  
Theanne N. Griffith ◽  
Jorge E. Contreras
Keyword(s):  
Purinergic Receptors ◽  
Pain Treatment ◽  
Purinergic Signaling ◽  
Atp Release ◽  
Current Evidence ◽  
Pain Processing ◽  
Potential Threat ◽  
Acute Response ◽  
Outstanding Question

AbstractPain is a physiological response to bodily damage and serves as a warning of potential threat. Pain can also transform from an acute response to noxious stimuli to a chronic condition with notable emotional and psychological components that requires treatment. Indeed, the management of chronic pain is currently an important unmet societal need. Several reports have implicated the release of the neurotransmitter adenosine triphosphate (ATP) and subsequent activation of purinergic receptors in distinct pain etiologies. Purinergic receptors are broadly expressed in peripheral neurons and the spinal cord; thus, purinergic signaling in sensory neurons or in spinal circuits may be critical for pain processing. Nevertheless, an outstanding question remains: what are the mechanisms of ATP release that initiate nociceptive signaling? Connexin and pannexin channels are established conduits of ATP release and have been suggested to play important roles in a variety of pathologies, including several models of pain. As such, these large-pore channels represent a new and exciting putative pharmacological target for pain treatment. Herein, we will review the current evidence for a role of connexin and pannexin channels in ATP release during nociceptive signaling, such as neuropathic and inflammatory pain. Collectively, these studies provide compelling evidence for an important role of connexins and pannexins in pain processing.

Ca2+ role in myogenic and neurogenic activities of canine ileum circular muscle

1996 ◽  
Vol 271 (6) ◽  
pp. G1053-G1066 ◽  
Author(s):  
F. S. Cayabyab ◽  
H. deBruin ◽  
M. Jimenez ◽  
E. E. Daniel
Keyword(s):  
Channel Blocker ◽  
Circular Muscle ◽  
Cyclopiazonic Acid ◽  
Membrane Potentials ◽  
Neural Activation ◽  
Lower Amplitude ◽  
Intact Muscle ◽  
Ca2 Channels ◽  
Muscularis Externa

The role of Ca2+ in myogenic and neural activation in canine ileum circular muscle (CM) was studied during simultaneous recordings of contractile and electrical activity in cross-sectioned slabs of muscularis externa or of isolated CM with deep muscular plexus (DMP) intact. Ca(2+)-free Krebs solution abolished inhibitory junction potentials (IJP) and contractions before changes in CM membrane potentials and while slow waves (SW) persisted at lower amplitude and frequency. This medium abolished SW more rapidly in isolated CM than in intact muscle strips and affected triggered SW (TSW) by 100-ms pulses recorded near myenteric plexus or near DMP differentially in the full-thickness preparation; TSW did not occur in isolated CM. Ni2+, a nonselective Ca2+ channel antagonist, left IJP unchanged and reduced contractions, frequencies, and amplitudes of spontaneous SW and TSW, but increased their durations. Nifedipine abolished contractions but SW, TSW, and IJP were unaffected. Cyclopiazonic acid (CPA) increased SW frequency, produced spikes on SW plateaus, and increased CM tone, but did not affect IJP or resting membrane potentials. In nifedipine-pretreated strips, CPA decreased SW frequencies and amplitudes, evoked less tone, depolarized membrane potentials, and left IJP unaltered. The neuronal N-type Ca2+ channel blocker omega-conotoxin GVIA abolished IJP, without affecting SW or TSW. We conclude that Ca2+ influx, not through L- or N-type Ca2+ channels, helps initiate ileal SW; L-type Ca2+ channels provide Ca2+ for contraction and N-type Ca2+ channels provide Ca2+ for IJP mediator release. Frequencies of SW may be modulated by uptake of Ca2+ into pacemaker stores.

scholarly journals Role of arachidonic acid lipoxygenase metabolites in acetylcholine-induced relaxations of mouse arteries

2011 ◽  
Vol 300 (3) ◽  
pp. H725-H735 ◽  
Author(s):  
Kathryn M. Gauthier ◽  
Daniel H. Goldman ◽  
Nitin T. Aggarwal ◽  
Yuttana Chawengsub ◽  
J. R. Falck ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Abdominal Aorta ◽  
Nordihydroguaiaretic Acid ◽  
Immunoblot Analysis ◽  
Mesenteric Arteries ◽  
Epoxyeicosatrienoic Acid ◽  
Resistance Arteries ◽  
Cox Inhibitor ◽  
Synthase Inhibitor

Arachidonic acid (AA) metabolites function as EDHFs in arteries of many species. They mediate cyclooxygenase (COX)- and nitric oxide (NO)-independent relaxations to acetylcholine (ACh). However, the role of AA metabolites as relaxing factors in mouse arteries remains incompletely defined. ACh caused concentration-dependent relaxations of the mouse thoracic and abdominal aorta and carotid, femoral, and mesentery arteries (maximal relaxation: 57 ± 4%, 72 ± 4%, 82 ± 3%, 80 ± 3%, and 85 ± 3%, respectively). The NO synthase inhibitor nitro-l-arginine (l-NA; 30 μM) blocked relaxations in the thoracic aorta, and l-NA plus the COX inhibitor indomethacin (10 μM) inhibited relaxations in the abdominal aorta and carotid, femoral, and mesenteric arteries (maximal relaxation: 31 ± 10%, 33 ± 5%, 41 ± 8%, and 73 ± 3%, respectively). In mesenteric arteries, NO- and COX-independent relaxations to ACh were inhibited by the lipoxygenase (LO) inhibitors nordihydroguaiaretic acid (NDGA; 10 μM) and BW-755C (200 μM), the K+ channel inhibitor apamin (1 μM), and 60 mM KCl and eliminated by endothelium removal. They were not altered by the cytochrome P-450 inhibitor N-methylsulfonyl-6-(2-propargyloxyphenyl)hexanamide (20 μM) or the epoxyeicosatrienoic acid antagonist 14,15-epoxyeicosa-5( Z)-enoic acid (10 μM). AA relaxations were attenuated by NDGA or apamin and eliminated by 60 mM KCl. Reverse-phase HPLC analysis revealed arterial [14C]AA metabolites that comigrated with prostaglandins, trihydroxyeicosatrienoic acids (THETAs), hydroxyepoxyeicosatrienoic acids (HEETAs), and hydroxyeicosatetraenoic acids (HETEs). Epoxyeicosatrienoic acids were not observed. Mass spectrometry confirmed the identity of 6-keto-PGF1α, PGE2, 12-HETE, 15-HETE, HEETAs, 11,12,15-THETA, and 11,14,15-THETA. AA metabolism was blocked by NDGA and endothelium removal. 11( R),12( S),15( S)-THETA relaxations (maximal relaxation: 73 ± 3%) were endothelium independent and blocked by 60 mM KCl. Western immunoblot analysis and RT-PCR of the aorta and mesenteric arteries demonstrated protein and mRNA expression of leukocyte-type 12/15-LO. Thus, in mouse resistance arteries, 12/15-LO AA metabolites mediate endothelium-dependent relaxations to ACh and AA.

Hydrogen sulfide as a mediator of endothelium-dependent relaxation evoked by Moringa oleifera leaf extract in mesenteric arterial beds isolated from L-NAME hypertensive rats

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Direk Aekthammarat ◽  
Panot Tangsucharit ◽  
Patchareewan Pannangpetch
Keyword(s):  
Nitric Oxide ◽  
Moringa Oleifera ◽  
Channel Blocker ◽  
Resistance Arteries ◽  
Hypertensive Rats ◽  
Nitric Oxide Synthase Inhibitor ◽  
Synthase Inhibitor ◽  
Gap Junctional ◽  
Oxide Synthase ◽  
Endothelium Dependent Relaxation

AbstractObjectivesAqueous extract of Moringa oleifera leaves (MOE) is a potent inducer of endothelium-dependent relaxation of mesenteric resistance arteries of rats induced to be hypertensive using Nω-nitro-L-arginine methyl ester (L-NAME). Hydrogen sulfide (H2S) has been shown to participate in endothelium-dependent relaxation of small resistance arteries. Therefore, this study aimed to investigate whether endothelial H2S-dependent signaling plays a role in the vasorelaxation in response to MOE.MethodsMesenteric arterial beds isolated from L-NAME hypertensive rats were set up in an ex vivo perfusion system for measurement of vasoreactivity. All experiments were performed in the presence of the nitric oxide synthase inhibitor, L-NAME (100 µM) and the cyclooxygenase inhibitor, indomethacin (10 µM) to prevent the formation of nitric oxide and prostanoids, respectively.ResultsIn the presence of the nitric oxide synthase inhibitor, L-NAME and the cyclooxygenase inhibitor, indomethacin, the endothelium-dependent vasorelaxation induced by MOE (0.001–3 mg) was completely inhibited by DL-propargylglycine (100 µM), which inhibits the H2Sgenerating enzyme, cystathionine γ-lyase. This H2Sdependent response was reduced by the KATP channel blocker; glibenclamide (10 µM), the KCa channel blocker; tetraethylammonium (1 µM), and the myo-endothelial gap-junctional uncoupler; 18α-glycyrrhetinic acid (10 µM). In contrast, the muscarinic receptor antagonist, atropine (100 µM), did not affect the response to MOE.ConclusionsThe results may suggest that H2S is the likely mediator of endothelium-dependent relaxation in response to MOE in mesenteric arterial beds of L-NAME-induced hypertensive rats. MOE-induced H2S-dependent vasorelaxation involves activation of KATP and KCa channels and requires myo-endothelial gap-junctional communication.

Prior episode of anoxia attenuates vasorelaxation in response to subsequent episode of anoxia

1994 ◽  
Vol 266 (3) ◽  
pp. H974-H979 ◽  
Author(s):  
B. C. Yang ◽  
J. L. Mehta
Keyword(s):  
Nitric Oxide ◽  
Methylene Blue ◽  
Superoxide Anion ◽  
Channel Blocker ◽  
Nitric Oxide Synthase Inhibitor ◽  
Subsequent Episode ◽  
Adenosine A1 ◽  
Synthase Inhibitor ◽  
Oxide Synthase

To examine the effect of a prior episode of anoxia on subsequent anoxia-mediated vasorelaxation, norepinephrine-precontracted endothelium-intact rat aortic rings were first exposed to anoxia (95% N2-5% CO2 for 5, 15, or 30 min) then to normoxia (95% O2-5% CO2 for 15 min). These rings were exposed again to anoxia for 30 min. First exposure of rings to anoxia for 30 min resulted in 77 +/- 4% decrease in tone (vasorelaxation), whereas second exposure resulted in only 10 +/- 4% relaxation (n = 11, P < 0.001 vs. relaxation during first exposure). First exposure of rings to anoxia for 5 or 15 min also diminished relaxation to 59 +/- 3 and 19 +/- 8%, respectively, on second exposure to anoxia (both P < 0.01 vs. relaxation during 1st anoxia). Attenuation of vasorelaxation by prior episode of anoxia was not affected by treatment of rings with indomethacin (10(-5) M), the Ca2+ channel blocker felodipine (10(-6) M), the superoxide anion scavenger superoxide dismutase (100 micrograms/ml), or adenosine A1 and A2 blockers (each 10(-6) M). To examine the role of intact functional endothelium in attenuation of vasorelaxation during second anoxic exposure, rings were deendothelialized and treated with the nitric oxide synthase inhibitor NG-monomethyl-L-arginine (L-NMMA; 10(-4) M) or the guanylate cyclase inhibitor methylene blue (MB; 2 x 10(-5) M). In all deendothelialized rings, vasorelaxation during second anoxic exposure was similar to that during first anoxic exposure (100 +/- 0 vs. 98 +/- 3%, P = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Calmodulin mediates norepinephrine-induced receptor-operated calcium entry in preglomerular resistance arteries

2005 ◽  
Vol 289 (1) ◽  
pp. F127-F136 ◽  
Author(s):  
Carie S. Facemire ◽  
William J. Arendshorst
Keyword(s):  
Calcium Concentration ◽  
Cyclopiazonic Acid ◽  
Calcium Entry ◽  
Resistance Arteries ◽  
Renal Vasculature ◽  
Resistance Vessels ◽  
Voltage Dependent ◽  
Voltage Dependent Calcium Channels ◽  
Entry Mechanism

Although L-type voltage-dependent calcium channels play a major role in mediating vascular smooth muscle cell contraction in the renal vasculature, non-L-type calcium entry mechanisms represent a significant component of vasoactive agonist-induced calcium entry in these cells as well. To investigate the role of these non-voltage-dependent calcium entry pathways in the regulation of renal microvascular reactivity, we have characterized the function of store- and receptor-operated channels (SOCs and ROCs) in renal cortical interlobular arteries (ILAs) of rats. Using fura 2-loaded, microdissected ILAs, we find that the L-type channel antagonist nifedipine blocks less than half the rise in intracellular calcium concentration ([Ca2+]i) elicited by norepinephrine. SOCs were activated in these vessels using the sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) inhibitors cyclopiazonic acid and thapsigargin and were dose dependently blocked by the SOC antagonists Gd3+ and 2-aminoethoxydiphenyl borate (2-APB) and the combined SOC/ROC antagonist SKF-96365. Gd3+ had no effect on the non-L-type Ca2+ entry activated by 1 μM NE. A low concentration of SKF-96365 that did not affect thapsigargin-induced store-operated Ca2+ entry blocked 60–70% of the NE-induced Ca2+ entry. Two different calmodulin inhibitors (W-7 and trifluoperazine) also blocked the NE-induced Ca2+ entry. These data suggest that in addition to L-type channels, NE primarily activates ROCs rather than SOCs in ILAs and that this receptor-operated Ca2+ entry mechanism is regulated by calmodulin. Interestingly, 2-APB completely blocked the NE-induced non-L-type Ca2+ entry, implying that SOCs and ROCs in preglomerular resistance vessels share a common molecular structure.

Smooth Muscle-Derived Nitric Oxide is Elevated in Isolated Forearm Veins in Human Alcoholic Cirrhosis

1996 ◽  
Vol 91 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Jeremy Ryan ◽  
Garry Jennings ◽  
Frank Dudley ◽  
Jaye Chin-Dusting
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Alcoholic Cirrhosis ◽  
Resistance Arteries ◽  
Nitric Oxide Synthase Inhibitor ◽  
Control Subjects ◽  
Synthase Inhibitor

1. Cirrhosis is often complicated by disturbances in the systemic circulation. We have previously demonstrated decreased vascular responses to vasoconstrictors in forearm resistance arteries in subjects with alcoholic cirrhosis. In the current study we investigate the role of the potent endogenous vasodilator nitric oxide in the peripheral circulation of these patients. 2. Ten patients with alcoholic cirrhosis (Pugh grade A) and 10 age-matched control subjects were studied. The effect of blockade of nitric oxide synthesis was studied both in vivo in forearm resistance arteries using forearm venous occlusion plethysmography and in vitro in veins isolated from the forearm. The role of endothelium-derived nitric oxide was studied in vivo using the endothelium-dependent vasodilator acetylcholine. 3. Mean arterial pressure and forearm basal flow in vivo were similar in the two groups. The constrictor response (percentage decrease in forearm blood flow) to noradrenaline (100 ng/min) was 26% smaller in patients with cirrhosis (31.65 ± 2.64%) than in control subjects (42.75 ± 3.87%, P = 0.037). Constrictor responses to the nitric oxide synthase inhibitor NG-monomethyl-l-arginine were not different in the two groups. Dilator responses to acetylcholine were significantly attenuated in cirrhotic patients compared with control subjects. 4. To investigate the role of smooth muscle-derived nitric oxide in vitro, all veins were stripped of their endothelium. Responses to noradrenaline were significantly diminished in veins isolated from patients with cirrhosis compared with control subjects. Incubation with the nitric oxide synthase inhibitor Nω-nitro-l-arginine had no effect on responses to noradrenaline in veins from control subjects but significantly enhanced the maximal response to noradrenaline by 23.95% (range 3.77–100%, P = 0.043) in veins from patients with cirrhosis. 5. Responses to noradrenaline were attenuated in vivo in forearm resistance arteries in patients with alcoholic cirrhosis. This impairment was also apparent in forearm isolated veins, stripped of the endothelium. Our data exclude a major role for endothelium-derived nitric oxide but highlight a possible role for smooth muscle-derived nitric oxide.

Abstract 15995: Role of Kir Channels in Flow-Induced Vasodilatation

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Sang Joon Ahn ◽  
Jing-Tan Bian ◽  
Sarah Schwab ◽  
Mary Szczurek ◽  
Shane A Phillips ◽  
...  
Keyword(s):  
Vascular Tone ◽  
Significant Inhibition ◽  
Dominant Negative ◽  
Mesenteric Arteries ◽  
Resistance Arteries ◽  
Nitric Oxide Synthase Inhibitor ◽  
Kir Channels ◽  
No Release ◽  
Synthase Inhibitor

Introduction: Flow-induced vasodilation (FIV) is an important physiological stimulus for regulating vascular tone. A loss of endothelial-dependent FIV is an early indication of endothelial dysfunction. Earlier studies proposed that endothelial inwardly-rectifying K + channels (Kir) are putative flow sensors, but the role of Kir in the regulation of vascular tone is not known. Hypothesis: Kir channels play a key role in FIV. Methods: FIV was assessed in mouse mesenteric arteries isolated from wild type (WT) and Kir2.1 +/- heterozygous mice. Briefly, resistance arteries were isolated, cannulated and pressurized in an organ chamber with glass micropipettes. Preparations were visualized in real time and the inner diameter of the vessels was measured using acquired images. Kir channels in arteries isolated from WT mice were downregulated by a dominant-negative subunit of Kir2.1 or blocked by Ba 2+ . The role of Kir channels in flow-induced release of NO was tested by Diaminorhodamine-4M, NO specific fluorescence dye. Results: Our results show that FIV is significantly inhibited in mesenteric arteries isolated from Kir2.1 +/- mice that have reduced Kir2.1 expression as compared with WT mice (42%±3% relaxation in Kir2.1 +/- vs 94.06%±2.2% in WT mice, n=11, p<0.05). Moreover, blocking Kir channels with Ba 2+ or downregulating its activity with a dominant-negative subunit of Kir2.1 also resulted in significant inhibition of FIV in arteries isolated from WT mice (47%±3% relaxation in the presence of Ba 2+ , 43%±5% in arteries infected with dnKir2.1 vs 94.06%±2.2% in WT n=3, p<0.05). As expected, inhibiting NO release by LNAME, a nitric oxide synthase inhibitor, reduced FIV in WT arteries (39%±5%, n=4, p<0.05), but no effect was observed in arteries isolated from Kir2.1 +/- mice. Furthermore, flow-induced release of NO was significantly reduced (1.5-fold decreased, p<0.05). In contrast, inhibiting Ca 2+ -dependent K + channels (SK/IK) had an additive effect to Kir suppression suggesting that SK/IK and Kir channels regulate FIV by parallel pathways. In conclusion, our results indicate that Kir channels contribute significantly to FIV by regulating NO release.

Platelet Aggregation in Whole Blood: The Role of Thromboxane A2 and Adenosine Diphosphate

1985 ◽  
Vol 54 (03) ◽  
pp. 612-616 ◽  
Author(s):  
A J Carter ◽  
S Heptinstall
Keyword(s):  
Platelet Aggregation ◽  
Whole Blood ◽  
Adenosine Diphosphate ◽  
Blood Platelet ◽  
Thromboxane B2 ◽  
Lipoxygenase Inhibitor ◽  
Thromboxane Synthase Inhibitor ◽  
Synthase Inhibitor

SummaryThe platelet aggregation that occurred in whole blood in response to several aggregating agents (collagen, arachidonic acid, adenosine diphosphate, adrenaline and thrombin) was measured using an Ultra-Flo 100 Whole Blood Platelet Counter. The amounts of thromboxane B2 produced were measured by radioimmunoassay. The effects of various inhibitors of thromboxane synthesis and the effects of apyrase, an enzyme that destroys adenosine diphosphate, were determined.Platelet aggregation was always accompanied by the production of thromboxane B2, and the amounts produced depended on the nature and concentration of the aggregating agent used. The various inhibitors of thromboxane synthesis - aspirin and flurbiprofen (cyclo-oxygenase inhibitors), BW755C (a cyclo-oxygenase and lipoxygenase inhibitor) and dazoxiben (a selective thromboxane synthase inhibitor) - did not markedly inhibit aggregation. Results obtained using apyrase showed that adenosine diphosphate contributed to the aggregation process, and that its role must be acknowledged when devising means of inhibiting platelet aggregation in vivo.

Collagen-Induced Platelet Aggregation: -Evidence Against the Essential Role of Platelet Adenosine Diphosphate

1979 ◽  
Vol 42 (04) ◽  
pp. 1193-1206 ◽  
Author(s):  
Barbara Nunn
Keyword(s):  
Platelet Aggregation ◽  
Time Course ◽  
Essential Role ◽  
Atp Release ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
High Doses ◽  
Induced Aggregation

SummaryThe hypothesis that platelet ADP is responsible for collagen-induced aggregation has been re-examined. It was found that the concentration of ADP obtaining in human PRP at the onset of aggregation was not sufficient to account for that aggregation. Furthermore, the time-course of collagen-induced release in human PRP was the same as that in sheep PRP where ADP does not cause release. These findings are not consistent with claims that ADP alone perpetuates a collagen-initiated release-aggregation-release sequence. The effects of high doses of collagen, which released 4-5 μM ADP, were not inhibited by 500 pM adenosine, a concentration that greatly reduced the effect of 300 μM ADP. Collagen caused aggregation in ADP-refractory PRP and in platelet suspensions unresponsive to 1 mM ADP. Thus human platelets can aggregate in response to collagen under circumstances in which they cannot respond to ADP. Apyrase inhibited aggregation and ATP release in platelet suspensions but not in human PRP. Evidence is presented that the means currently used to examine the role of ADP in aggregation require investigation.

Sign in / Sign up

Export Citation Format

Share Document