Hyposmotic stress triggers ATP release from porcine lens via connexin and pannexin hemichannels

2011 ◽  
Vol 89 (s248) ◽  
pp. 0-0
Author(s):  
NA DELAMERE ◽  
C BEIMGRABEN ◽  
A MANDAL ◽  
M SHAHIDULLAH
Keyword(s):  
Atp Release ◽  
Hyposmotic Stress

scholarly journals TRPV4 in porcine lens epithelium regulates hemichannel-mediated ATP release and Na-K-ATPase activity

2012 ◽  
Vol 302 (12) ◽  
pp. C1751-C1761 ◽  
Author(s):  
Mohammad Shahidullah ◽  
Amritlal Mandal ◽  
Nicholas A. Delamere
Keyword(s):  
Atpase Activity ◽  
Atp Release ◽  
Calcium Entry ◽  
Glycyrrhetinic Acid ◽  
Lens Epithelium ◽  
Transient Receptor Potential Vanilloid ◽  
Bathing Solution ◽  
Cytoplasmic Calcium ◽  
Bathing Medium ◽  
Hyposmotic Stress

In several tissues, transient receptor potential vanilloid 4 (TRPV4) channels are involved in the response to hyposmotic challenge. Here we report TRPV4 protein in porcine lens epithelium and show that TRPV4 activation is an important step in the response of the lens to hyposmotic stress. Hyposmotic solution (200 mosM) elicited ATP release from intact lenses and TRPV4 antagonists HC 067047 and RN 1734 prevented the release. In isosmotic solution, the TRPV4 agonist GSK1016790A (GSK) elicited ATP release. When propidium iodide (PI) (MW 668) was present in the bathing medium, GSK and hyposmotic solution both increased PI entry into the epithelium of intact lenses. Increased PI uptake and ATP release in response to GSK and hyposmotic solution were abolished by a mixture of agents that block connexin and pannexin hemichannels, 18α-glycyrrhetinic acid and probenecid. Increased Na-K-ATPase activity occurred in the epithelium of lenses exposed to GSK and 18α-glycyrrhetinic acid + probenecid prevented the response. Hyposmotic solution caused activation of Src family kinase and increased Na-K-ATPase activity in the lens epithelium and TRPV4 antagonists prevented the response. Ionomycin, which is known to increase cytoplasmic calcium, elicited ATP release, the magnitude of which was no greater when lenses were exposed simultaneously to ionomycin and hyposmotic solution. Ionomycin-induced ATP release was significantly reduced in calcium-free medium. TRPV4-mediated calcium entry was examined in Fura-2-loaded cultured lens epithelium. Hyposmotic solution and GSK both increased cytoplasmic calcium that was prevented by TRPV4 antagonists. The cytoplasmic calcium rise in response to hyposmotic solution or GSK was abolished when calcium was removed from the bathing solution. The findings are consistent with hyposmotic shock-induced TRPV4 channel activation which triggers hemichannel-mediated ATP release. The results point to TRPV4-mediated calcium entry that causes a cytoplasmic calcium increase which is an essential early step in the mechanism used by the lens to sense and respond to hyposmotic stress.

Hyposmotic stress causes ATP release and stimulates Na,K-ATPase activity in porcine lens

2012 ◽  
Vol 227 (4) ◽  
pp. 1428-1437 ◽  
Author(s):  
M. Shahidullah ◽  
A. Mandal ◽  
C. Beimgraben ◽  
N.A. Delamere
Keyword(s):  
Atpase Activity ◽  
Atp Release ◽  
Hyposmotic Stress

498: ATP Release from Human Bladders with Sensory Disorder vs Normal Bladders

2004 ◽  
Vol 171 (4S) ◽  
pp. 133-133
Author(s):  
Vivekanandan Kumar ◽  
Christopher R. Chapple ◽  
Russell Chess-Williams
Keyword(s):  
Atp Release

Chlorobutanol, a Preservative of Desmopressin, Inhibits Human Platelet Aggregation and Release In Vitro

1990 ◽  
Vol 64 (03) ◽  
pp. 473-477 ◽  
Author(s):  
Shih-Luen Chen ◽  
Wu-Chang Yang ◽  
Tung-Po Huang ◽  
Shiang Wann ◽  
Che-ming Teng
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Atp Release ◽  
Free Calcium ◽  
Dependent Manner ◽  
Antiplatelet Effect ◽  
Human Platelet Aggregation ◽  
Acid Pathway ◽  
Arachidonic Acid Pathway

SummaryTherapeutic preparations of desmopressin for parenteral use contain the preservative chlorobutanol (5 mg/ml). We show here that chlorobutanol is a potent inhibitor of platelet aggregation and release. It exhibited a significant inhibitory activity toward several aggregation inducers in a concentration- and time-dependent manner. Thromboxane B2 formation, ATP release, and elevation of cytosolic free calcium caused by collagen, ADP, epinephrine, arachidonic acid and thrombin respectively were markedly inhibited by chlorobutanol. Chlorobutanol had no effect on elastase- treated platelets and its antiplatelet effect could be reversed. It is concluded that the antiplatelet effect of chlorobutanol is mainly due to its inhibition on the arachidonic acid pathway but it is unlikely to have a nonspecitic toxic effect. This antiplatelet effect of chlorobutanol suggests that desmopressin, when administered for improving hemostasis, should not contain chlorobutanol as a preservative.

Trimucytin: A Collagen-Like Aggregating Inducer Isolated from Trimeresurus mucrosquamatus Snake Venom

1993 ◽  
Vol 69 (03) ◽  
pp. 286-292 ◽  
Author(s):  
Che-Ming Teng ◽  
Feng-Nien Ko ◽  
Inn-Ho Tsai ◽  
Man-Ling Hung ◽  
Tur-Fu Huang
Keyword(s):  
Platelet Aggregation ◽  
Snake Venom ◽  
Inositol Phosphate ◽  
Shape Change ◽  
Platelet Activating Factor ◽  
Atp Release ◽  
Platelet Membrane ◽  
Thromboxane B2 ◽  
Dependent Manner ◽  
Concentration Dependent Manner

SummaryTrimucytin is a potent platelet aggregation inducer isolated from Trimeresurus mucrosquamatus snake venom. Similar to collagen, trimucytin has a run of (Gly-Pro-X) repeats at the N-terminal amino acids sequence. It induced platelet aggregation, ATP release and thromboxane formation in rabbit platelets in a concentration-dependent manner. The aggregation was not due to released ADP since it was not suppressed by creatine phosphate/creatine phosphokinase. It was not either due to thromboxane A2 formation because indomethacin and BW755C did not have any effect on the aggregation even thromboxane B2 formation was completely abolished by indomethacin. Platelet-activating factor (PAF) was not involved in the aggregation since a PAF antagonist, kadsurenone, did not affect. However, RGD-containing peptide triflavin inhibited the aggregation, but not the release of ATP, of platelets induced by trimucytin. Indomethacin, mepacrine, prostaglandin E1 and tetracaine inhibited the thromboxane B2 formation of platelets caused by collagen and trimucytin. Forskolin and sodium nitroprusside inhibited both platelet aggregation and ATP release, but not the shape change induced by trimucytin. In quin-2 loaded platelets, the rise of intracellular calcium concentration caused by trimucytin was decreased by 12-O-tetradecanoyl phorbol-13 acetate, imipramine, TMB-8 and indomethacin. In the absence of extracellular calcium, both collagen and trimucytin caused no thromboxane B2 formation, but still induced ATP release which was completely blocked by R 59022. Inositol phosphate formation in platelets was markedly enhanced by trimucytin and collagen. MAB1988, an antibody against platelet membrane glycoprotein Ia, inhibited trimucytinand collagen-induced platelet aggregation and ATP release. However, trimucytin did not replace the binding of 125I-labeled MAB1988 to platelets. Platelets pre-exposed to trimucytin were resistant to the second challenge with trimucytin itself or collagen. It is concluded that trimucytin may activate collagen receptors on platelet membrane, and cause aggregation and release mainly through phospholipase C-phosphoinositide pathway.

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.

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