Non-Destructive Micro-Measurement Techniques Paper Part V.

Part V. Cell Physiology and Diseases
17. Mechanisms by which Ca2+ channels manipulated by the calcium pool prevent ischemia-reperfusion injury in the rat liver
Hepatic ischemia-reperfusion injury (HIRI) has a wide range of implications for clinical diagnosis and surgical status, including hemorrhagic shock, liver trauma, and hepatectomy.HIRI leads to liver disorders and even loss of function, so how to avoid HIRI is a major medical challenge.Ca2+ plays a key role in HIRI because Ca2+ activates Ca2+-dependent phosphodiesterases, nucleases and proteases, as well as oxidative phosphorylation

In order to understand the mechanism of Ca2+ in HIRI, in January 2012, a collaborative study between Zongming Zhang's lab at Tsinghua University and Asahiyuki Corporation on the mechanism of Ca2+ pool-operated Ca2+ channels (SOCs) preventing ischemia-reperfusion injury in rat liver was published in the World Journal of Gastroenterology. The objectives of the study were to further confirm the importance of SOCs in rat hepatocytes, to discover the effects of SOCs in HIRI, and to investigate the potential use of SOC inhibitors for HIRI protection. In the study, various changes in acutely isolated hepatocytes from HIRI model rats were experimentally measured using non-invasive micro-metering techniques, Ca2+ imaging and membrane clamp, and it was found that Ca2+ oscillations and Ca2+ flow rates were regulated by Ca2+ in-flow from SOCs and that La3+ inhibited SOC currents.

This study revealed an important role of SOCs in HIRI, namely that SOC inhibitors protect HIRI and aid in the repair of hepatocyte secretory function. Therefore, this inhibitor is likely to be used as an effective drug for the treatment of HIRI patients in the future.

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Figure Note: Ca2+ flow rate of acutely isolated rat hepatocytes after different inhibitor treatments.

Pan LJ, et al. Effects and mechanisms of store-operated calcium channel blockade on hepatic ischemia-reperfusion injury in rats. World Journal of Gastroenterology, 2012, 18(4): 356-367. (2011 IF 2.24)

18. K+ and Cl- are uncoupled during volume reduction in nasopharyngeal carcinoma cells
Cell volume regulation underlies various cellular functions such as cell division, cell proliferation, apoptosis, cell migration and cell regulation, all of which require changes in cell volume and the involvement of transmembrane ions. Volume change activated K+ and Cl- channels have been extensively studied using membrane clamp and found to be K+- tightly coupled in the regulation of volume reduction (RVD).

In May 2012, the results of Prof. Liwei Wang's group at the School of Medicine of Jinan University were published in the international pharmacology journal Biochemical Pharmacology. It was found that hypotonicity decreased intracellular pH (pHi) and activated proton pump-dependent H+ efflux, leading to a decrease in extracellular pH (pHo). The moderate decrease in pHo inhibited volume-activated K+ efflux and RVD, but not Cl- efflux, and promoted K+ efflux and RVD when H+ efflux was inhibited or the buffering capacity of pHo was increased. this result indicates that in RVD process the kinetics of K+ channels differ from that of Cl- channels due to the different sensitivity of K+ and Cl- channels to pHo.

This is the first finding that K+ and Cl- transport is not coupled (uncoupled) during hypotonicity-induced RVD and that H+ efflux plays an important role in cell volume regulation and may be a target for the treatment of nasopharyngeal carcinoma. The use of non-invasive micrometry in this work overcame the limitations of the membrane clamp technique that cannot measure live cells and long-term measurements, and the results of the study have changed the understanding of RVD.

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Figure Note: Effect of hypotonicity on H+ flow rate in nasopharyngeal carcinoma cells.

Yang LJ, et al. Uncoupling of K+ and Cl- transport across the cell membrane in the process of regulatory volume decrease. biochemical Pharmacology, 2012, 84(3): 292-302. (2011 IF 4.705)

Part VI Environmental Sciences
19. Pathways of Cd2+ uptake by alkali poncho roots
Cd2+ is a common heavy metal in the environment, which causes serious damage to plant growth and development. Research in recent years has revealed that we can absorb Cd2+ from the environment through phytoremediation. The salt plant Alkali poncho can survive in high salt concentration and also adapt to the environment of heavy metals, therefore, Alkali poncho may serve as a plant for remediation of heavy metal environment.

In early 2012, Wu Huifeng's group at the Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences published a paper entitled "Pathways of cadmium fluxes in the root of the halophyte Suaeda salsa". In this study, the pathways of Cd2+ uptake in the halophyte Suaeda salsa during phytoremediation were investigated using the non-damage microtesting technique (NMT, denoted by SIET in the paper), and the pattern of Cd2+ uptake in different regions of the root tip was found. It was also inhibited by the sulfhydryl blocker N-ethylmaleimide (N-ethylmaleimide).

The results suggest that saline and sweet-soil plants have similar Cd2+ transport systems that are regulated by Ca2+ channels, which provides a theoretical basis for phytoremediation of Cd2+

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Note: Plots of Cd2+ inward flow in alkali poncho roots at measured and different points. Negative values are Cd2+ inward flow.

Li LZ, et al. Pathways of cadmium fluxes in the root of the halophyte Suaeda salsa. Ecotoxicology and Environmental Safety, 2012, 75(1): 1-7. (2011 IF 2.294)

20. Physiological mechanisms of fungal H+, O2 and Cd2+ flow rates and environmental pollution
The use of microorganisms for environmental remediation is very valuable in environmental management because of the cheapness, environmental friendliness, and the ability to efficiently remove a wide range of environmental pollutants. White-rot fungi are very effective lignin degraders, and representative species such as Xanthospora protostriatalis flatus, have been used to degrade organic pollutants.

In June 2012, Guangming Zeng and Guiqiu Chen's laboratory in the School of Environmental Science and Engineering of Hunan University published a paper entitled "Responses of Phanerochaete chrysosporium to toxic pollutants: physiological flux, oxidative stress, and detoxification". In the study, H+, O2, and Cd2+ fluxes of the white rot fungus Phanerochaete chrysosporium were measured in real time using the noninvasive microtest technique (NMT) in response to exposure to the environmental toxicants 2,4-DCP and Cd2+. Significant changes in the flow rates of H+ and O2 were found under exposure to 10 mg/L of 2,4-DCP and 0.1 mM of Cd2+, and such changes in flow rates were associated with oxidative stress.

The study in this paper promotes the understanding of the physiological response of fungi to toxicants, illustrates the mechanism of this response, and provides new techniques and ideas for fungal-based wastewater treatment.

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Note: Variation of H+ and O2 flow rates of the white rot fungus Trichoderma flavus under 2,4-DCP and Cd2+ treatment. Positive values are outward flow and negative values are inward flow.

Zeng GM, et al. Responses of Phanerochaete chrysosporium to toxic pollutants: physiological flux, oxidative stress, and detoxification. Environmental Science & Technology, 2012, 46(14): 7818-7825. (2011 IF 5.228)