Unexpected Relationship of Extracellular ATP with Intracellular Ca Concentration in HepG2 Cells

The aim of our study is to examine the effect of extracellular ATP whether it is correlated with intracellular Ca concentrations ([Ca2+]i) on human liver hepatocellular cells (HepG2). The extracellular ATP is responsible for regulating both cells signaling and cell functions. ATP maintains these effects through purinergic P2 receptors. The extracellular ATP promotes the release of Ca2+ from the Ca2+ stores to the cytoplasm in the cell and increases [Ca2+] I in the cell. In our study, various concentrations of ATP (10-3M-10-7M) were applied to HepG2 cells and incubated for 24 hours, 48 hours, and 72 hours. At these concentrations, the proliferation of cells and apoptosis of the cells was examined for 24 hours, 48 hours, and 72 hours. Similarly, cells with different ATP concentrations incubated for 24 hours and 48 hours were loaded with Indo 1FF AM calcium indicator to measure [Ca2+]i. Surprising results were obtained, 10-6M-10-7M extracellular ATP was found to be more toxic than 10-3 M-10-4 M extracellular ATP, (p<0.05). Low concentrations of ATP also reduced [Ca2+]i for 24 hours and 48 hours of incubations (p<0.01). As a result, low concentration extracellular ATP is more toxic in HepG2 cells. At the same time, the extracellular ATP correlates with [Ca2+]i.

Regulation of extracellular ATP onchlorophyll content and fluorescence characteristics of Angelica sinensis seedlings under drought and low temperature stress / 中国中药杂志

As an important signal molecule, extracellular ATP(eATP) can regulate many physiological and biochemical responses to plant stress. In this study, the regulation of extracellular ATP(eATP) on chlorophyll content and chlorophyll fluorescence parameters of Angelica sinensis seedlings were studied under drought and low temperature stress. The results showed that all the chlorophyll content, the actual photochemical efficiency [Y(Ⅱ)], the electron transfer rate(ETR), the photochemical quenching coefficient(qP and qL) of A. sinensis leaves were significantly decreased under drought and low temperature stress, respectively. At the same time, non-photochemical quenching(NPQ and qN) were also all significantly increased, respectively. The application of eATP alleviated the decrease of chlorophyll content, Y(Ⅱ), ETR, qP and qL of A. sinensis leaves under drought and low temperature stress, and eliminated the increase of qN and NPQ. The results indicated that eATP could effectively increase the open ratio of PSⅡ reaction centers, and improve the electron transfer rate and light energy conversion efficiency of PSⅡ of A. sinensis leaves under drought and low temperature stress. It is beneficial to enhance the chlorophyll synthesis and the adaptability of PSⅡ about A. sinensis seedlings to drought and low temperature stress.

Nucleoside Diphosphate Kinase from Microorganisms

Nucleoside diphosphate kinase (Ndk) is ubiquitous and highly conserved multifunctional key enzyme in nucleotide metabolism. It generates nucleoside triphosphates (NTPs) by transfer of gamma-phosphates from nucleoside triphosphates such as ATP or GTP to nucleoside diphosphate. The formation of an autophosphorylated enzyme intermediate is involved in that mechanism. The phosphate is usually supplied by ATP and Ndk activity in different subcellular compartments. Ndk may regulate the crucial balance between ATP and GTP or other nucleoside triphosphates. Ndk is playing an important role in bacterial pathogenesis and emerging evidences recognize multiple roles of Ndk in host-microbe interaction. Here, I review some examples of the role of Ndk in intra- and extracellular microorganism.

The effect on sciatic nerve regeneration of non-selective antagonist of ATP receptors / 中华显微外科杂志

Objective To prove the extracellular ATP attracts the axonal regeneration after peripheral nerve injury via the ATP receptor Methods The sciatic nerve defects had been made in 10 female Sprague Danley rats and repaired by"Y" form silicon tube The single arm of the"Y" form tube were sutured with the proxma the sciatic nerve and the other two end of silicon tube sutured by paralled or cross method so as to differentiate the experimental side and control side, 1mmol/L 10 ?l ATP and 1mmol/L 10 ?m ATP+ 0 2mg/ml Suramin were injected differently into two arms of left side and 10 ?l physiological saling and 10 ?l 0 2mg/ml Suramin injected differently into two arms of right dide The silicon tube were removed after eight weeks and examine the form and number of myelinated tibers as well as the quanlity of the myelinated sheath Results In the left sides regeneration axon were tuned into the silicon tubes containing the ATP and there were not axon regeneration in the silicon tube contained the ATP and there were not axon regeneration in the silicon tube contained ATP+ Suramin In the right sides the regeneration axon were found only three tubes contained suramin and seven tubes contained physiological saline Conclusions The results demonstrated that the suramin inhibited the axon reduction of the extracellular ATP completely