Involvement of Thromboxane A2 in the Modulation of Pacemaker Activity of Interstitial Cells of Cajal of Mouse Intestine

Although many studies show that thromboxane A2 (TXA2) has the action of gastrointestinal (GI) motility using GI muscle cells and tissue, there are no reports on the effects of TXA2 on interstitial cells of Cajal (ICC) that function as pacemaker cells in GI tract. So, we studied the modulation of pacemaker activities by TXA2 in ICC with whole cell patch-clamp technique. Externally applied TXA2 (5 micrometer) produced membrane depolarization in current-clamp mode and increased tonic inward pacemaker currents in voltage-clamp mode. The tonic inward currents by TXA2 were inhibited by intracellular application of GDP-beta-S. The pretreatment of ICC with Ca2+ free solution and thapsigargin, a Ca2+-ATPase inhibitor in endoplasmic reticulum, abolished the generation of pacemaker currents and suppressed the TXA2-induced tonic inward currents. However, chelerythrine or calphostin C, protein kinase C inhibitors, did not block the TXA2-induced effects on pacemaker currents. These results suggest that TXA2 can regulate intestinal motility through the modulation of ICC pacemaker activities. This modulation of pacemaker activities by TXA2 may occur by the activation of G protein and PKC independent pathway via extra and intracellular Ca2+ modulation.

Effect of Jiuqiang Naoliqing on the TXA_2 and PGI_2 level in spontaneous hypertension rat plasma / 中国康复理论与实践

@#ObjectiveTo investigate the effect of Jiuqiang Naoliqing(JNQ) on the TXA2 and PGI2 level in spontaneous hypertension rat (SHR) plasma.MethodsThe plasma was separated after the SHR and Wistar rats were treated with JNQ at the dose of 0.133g/kg,0.265g/kg,0.530g/kg and 1% carboxymethyl cellulose respectively for 5 weeks. The level of TXB2 and 6 keto PGF1α ,stable metabolin of TXA2 and PGI 2,in SHR plasma was tested by radioimmunoassay.ResultsThe level of TXB2 and the ratio of TXB2/6 keto PGF1α (T/P) in SHR plasma increased significantly(P<0.01),and there was no significant difference in the concentration of 6 keto PGF1α between Wistar rats and SHR plasma(P>0.05). JNQ could increase the generation of 6 keto PGF1α and decrease the level of TXB2 and T/P in SHR plasma after treated with different dosages for 5 weeks.ConclusionJNQ may improve the balance between TXA2 and PGI2 in SHR plasma.

Effect of CLA (Conjugated Linoleic Acid) on the Anti-Atherosclerotic Factors in Human Hepatoma HepG2 Cells

Conjugated linoleic acid (CLA) is the mixture of positional and geometric isomers of linoleic acid (LA), which is found abundantly in dairy products and meats. This study was performed to investigate the anticarcinogenic effect of CLA in HepG2 hepatoma cells. HepG2 cell were treated with LA and CLA at the various concentrations of 10, 20, 40, 80 uM each at different incubation times. After each incubation times, cell proliferation, fatty acids incorporation into cell, peroxidation and postaglandin E2 (PGE2) and thromboxane A2 (TXA2) for the eicosanoid metabolism were measured. LA treated HepG2 cells were increased cell growth 6 - 70% of control whereas CLA increased cell death the half of those in LA group (p < 0.001). LA and CLA were incorporated very well into the cellular membranes four times higher than in control according to concentration and longer incubation times. Moreover, LA synthesized significantly arachidonic acids corresponding with LA concentration compared to CLA supplementation. The supplementation with LA increased intracellular lipid peroxides concentration corresponding with LA concentration and five times higher than those in CLA significantly at any incubation times (p < 0.001). PGE2 and TXA2 levels were three to twenty times lower in condition of CLA treatments than LA, respectively. Overall, the dietary CLA might change the HepG2 cell growth by the changes of cell composition, production of lipid peroxide. Since CLA have not changed the levels of arachidonic acid of cell membrane, which was sources of eicosanoids, eicosanoid synthesis was not increased in CLA compared to LA. Our results was suggest CLA has a possibility to protect the progress of atherosclerosis because CLA does not produce lipid production and endothelial contraction factors in liver.

Thromboxane A_2/prostacyclin and pulmonary hypertension secondary to congenital heart disease / 实用儿科临床杂志

Objective To study the relationship between TXA 2/PGI2 and pulmonary hypertension in Congenital Heart Disease(CHD).Methods The serum concentration of TXB2/6-K-PGF1? was determined in 63 patients with CHD by radioimmunoassay. Results TXB2 ，TXB2 /6-K-PGF1? increased significantly in P H,while 6-K-PGF1? decreased,the TXB2 /6-K-PGF1? varied in different PH groups(P＜0.05).Conclusion TXA2/PGI2 plays an important role in the pathogenesis of PH se- condary to CHD.

THE INFLUENCES OF AMMONIUM GLYCYRRHIZANATE AGON PROSTAGLANDIN(PG) AND DNA BIOSYNTHESIS IN CULTURED RAT AND HUMAN LYMPHOCYTES / 中国药理学通报

The influences of varied concentrations of AG on the 8H-TdR(3H-Thymidine ) incorporation inhibition rate and the release of PGI2 and TXA2 were studied in cultured human and rat lymphocytes . The results indicated that the AG increased the 3H-TdR incorporation inhibition rate on the concentrations of 1.5? 10-7mol/L and 3?10-7mol/L. Using the RIA method, authors find that AG on the concentrations of 4 ? 10-7mol/L, 4 ? 10-3mol/L and 4 ? 10-11mo/L can significantly decrease the cultured lymphocytes TXA2 release while has no clear influences on PGI2 release