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이노시톨 삼인산 수용체와 미토콘드리아에 의한 심방 근세포 $Ca^{2+}$ 신호전달의 조절
이향진,라스클리만,마틴모라드,우선희,Lee , Hyang-Jin,Cleemann , Lars,Morad , Martin,Woo, Sun-Hee 대한약학회 2004 약학회지 Vol.48 No.6
Atrial myocytes have two functionally separate groups of ryanodine receptors (RyRs): those at the periphery colocalized with L-type $Ca^{2+}$channels (DHPRS) and those a t the cell interior not associated with DHPRs. $Ca^{2+}$ current ($I_{ca}$) directly gates peripheral RyRs on action potential and the subsequent peripheral $Ca^{2+}$ release propagates into the center of atrial myocytes. The mechanisms that regulate the $Ca^{2+}$+ propagation wave remain Poorly understood. Using 2-D confocal$Ca^{2+}$ imaging, we examined the role of inositol 1,4,5-trisphosphate receptor (IP $_3R$) and mitochondria on ($I_{ca}$)- gated local $Ca^{2+}$ signaling in rat atrial myocytes. Blockade of IP $_3R$ by xestospongin C (XeC) partially suppressed the magnitudes of I ca-gated central and peripheral $Ca^{2+}$ releases with no effect on $I_{ca}$. Mitochondrial staining revealed that mitochondria were aligned with ${\thickapprox}2-{\mu}m$ separations in the entire cytoplasm of ventricular and atrial myocytes. Membrane depolarization induced rapid mitochondrial $Ca^{2+}$ rise and decay in the cell periphery with slower rise in the center, suggesting that mitochondria may immediately uptake cytosolic $Ca^{2+}$, released from the peripheral SR on depolarization, and re-release the $Ca^{2+}$ into the cytosol to activate neighboring central RyRs. Our data suggest that the activation of IP $_3R$ and mitochondrial $Ca^{2+}$ handing on action potential may serve as a cofactor for the $Ca^{2+}$ propagation from the DHPR-coupled RyRs to the DHPR-uncoupled RyRs with large gaps between them.
Tetrazole substituted polymers for high temperature polymer electrolyte fuel cells
Henkensmeier, Dirk,Duong, Ngoc My Hanh,Brela, Mateusz,Dyduch, Karol,Michalak, Artur,Jankova, Katja,Cho, Hyeongrae,Jang, Jong Hyun,Kim, Hyoung-Juhn,Cleemann, Lars N.,Li, Qingfeng,Jensen, Jens Oluf The Royal Society of Chemistry 2015 Journal of Materials Chemistry A Vol.3 No.27
<▼1><P>Tetrazole (TZ) has lower basicity than imidazole and may not be fully protonated by phosphoric acid. DFT calculations suggest that the basicity of TZ groups can be increased by introducing a 2,6-dioxy-phenyl-group in position 5.</P></▼1><▼2><P>While tetrazole (TZ) has much lower basicity than imidazole and may not be fully protonated in the presence of phosphoric acid (PA), DFT calculations suggest that the basicity of TZ groups can be increased by the introduction of a 2,6-dioxy-phenyl-group in position 5 of TZ. This structure allows hydrogen bonds between TZ protons and ether oxygen atoms, and thereby establishes a resonance stabilised, co-planar structure for tetrazolium ions. Molecular electrostatic potential (MEP) calculations also indicate that tetrazolium ions possess two sites for proton hopping. This makes such materials interesting for use in a high temperature fuel cell (HT PEMFC). Based on these findings, two polymers incorporating the proposed TZ groups were synthesised, formed into membranes, doped with PA and tested for fuel cell relevant properties. At room temperature, TZ-PEEN and commercial <I>meta</I>-PBI showed an equilibrium uptake of 0.5 and 4.7 mol PA per mol heterocycle, respectively, indicating that PBI has higher affinity for PA than TZ-PEEN. The highest achieved PA uptake was <I>ca.</I> 110 wt%, resulting in a proton conductivity of 25 mS cm<SUP>−1</SUP> at 160 °C with a low activation energy of about 35 kJ mol<SUP>−1</SUP>. In a first HT PEMFC test at 160 °C, a peak power density of 287 mW cm<SUP>−2</SUP> was achieved.</P></▼2>