ABSTRACT
A comprehensive collection of proteins senses local changes in intracellular Ca²âº concentrations ([Ca²âº]i) and transduces these signals into responses to agonists. In the present study, we examined the effect of sphingosine-1-phosphate (S1P) on modulation of intracellular Ca²âº concentrations in cat esophageal smooth muscle cells. To measure [Ca²âº]i levels in cat esophageal smooth muscle cells, we used a fluorescence microscopy with the Fura-2 loading method. S1P produced a concentration-dependent increase in [Ca²âº]i in the cells. Pretreatment with EGTA, an extracellular Ca²âº chelator, decreased the S1P-induced increase in [Ca²âº]i, and an L-type Ca²âº-channel blocker, nimodipine, decreased the effect of S1P. This indicates that Ca²âº influx may be required for muscle contraction by S1P. When stimulated with thapsigargin, an intracellular calcium chelator, or 2-Aminoethoxydiphenyl borate (2-APB), an InsP3 receptor blocker, the S1P-evoked increase in [Ca²âº]i was significantly decreased. Treatment with pertussis toxin (PTX), an inhibitor of Gi-protein, suppressed the increase in [Ca²âº]i evoked by S1P. These results suggest that the S1P-induced increase in [Ca²âº]i in cat esophageal smooth muscle cells occurs upon the activation of phospholipase C and subsequent release of Ca²âº from the InsP3-sensitive Ca²âº pool in the sarcoplasmic reticulum. These results suggest that S1P utilized extracellular Ca²âº via the L type Ca²âº channel, which was dependent on activation of the S1P4 receptor coupled to PTX-sensitive Gi protein, via phospholipase C-mediated Ca²âº release from the InsP3-sensitive Ca²âº pool in cat esophageal smooth muscle cells.
ABSTRACT
In this study, we investigated the effects of pelargonidin, an anthocyanidin found in many fruits and vegetables, on endothelium-independent vascular contractility to determine the underlying mechanism of relaxation. Isometric contractions of denuded aortic muscles from male rats were recorded, and the data were combined with those obtained in western blot analysis. Pelargonidin significantly inhibited fluoride-, thromboxane A2-, and phorbol ester-induced vascular contractions, regardless of the presence or absence of endothelium, suggesting a direct effect of the compound on vascular smooth muscles via a different pathway. Pelargonidin significantly inhibited the fluoride-dependent increase in the level of myosin phosphatase target subunit 1 (MYPT1) phosphorylation at Thr-855 and the phorbol 12,13-dibutyrate-dependent increase in the level of extracellular signal-regulated kinase (ERK) 1/2 phosphorylation at Thr202/Tyr204, suggesting the inhibition of Rho-kinase and mitogen-activated protein kinase kinase (MEK) activities and subsequent phosphorylation of MYPT1 and ERK1/2. These results suggest that the relaxation effect of pelargonidin on agonist-dependent vascular contractions includes inhibition of Rho-kinase and MEK activities, independent of the endothelial function.
ABSTRACT
The use of multiple donors in an active layer is an effective way to boost the efficiency of organic solar cells by broadening their absorption window. Here, we report an efficient vacuum-deposited ternary organic photovoltaic (OPV) using two donors, 2-((2-(5-(4-(diphenylamino)phenyl)thieno[3,2-b]thiophen-2-yl)thiazol-5-yl)methylene)malononitrile (DTTz) for visible absorption and 2-((7-(5-(dip-tolylamino)thiophen-2-yl)benzo[c]-[1,2,5]thiadiazol-4-yl)methylene)malononitrile (DTDCTB) for near-infrared absorption, codeposited with C70 in the ternary layer. The ternary device achieved a power conversion efficiency of 8.02%, which is 23% higher than that of binary OPVs. This enhancement is the result of incorporating two donors with complementary absorption covering wavelengths of 350 to 900 nm with higher hole mobility in the ternary layer than that of binary layers consisting of one donor and C70, combined with energy transfer from the donor with lower hole mobility (DTTz) to that with higher mobility (DTDCTB). This structure fulfills all the requirements for efficient ternary OPVs.
ABSTRACT
We report that the crystallinity of C70 is improved significantly if CuI is used as a templating layer, leading to remarkable enhancement of hole mobilities from 8.32 × 10(-6) to 3.26 × 10(-5) cm(2)/(V s). As a result, the use of the templating layer in C70-based solar cells with low donor concentration resulted in significant improvement of the fill factor from 0.51 to 0.57 and the power conversion efficiency from 5.56% to 6.23% under simulated AM 1.5G, 1 sun irradiation. This result demonstrates that the CuI templating layer is effective at improving the crystallinity of the fullerene derivatives as well as the donor materials.
ABSTRACT
The molecular orientation and crystallinity of donor and acceptor molecules are important for high-efficiency organic photovoltaic cells (OPVs) because they significantly influence both the absorption of light and charge-transport characteristics. We report that the templating effect extends to multilayers to increase the crystallinity and to modify the orientation of the crystals of lead phthalocyanine (PbPc) and C70 layers at the same time by adopting CuBr as a new templating layer on indium tin oxide (ITO). The formation of a monoclinic phase with a preferred orientation of (320) for PbPc and a fcc phase with a preferred orientation of (220) for C70 on the PbPc layer is revealed by X-ray diffraction (XRD) patterns. The multilayer epitaxy results in an increase of the exciton diffusion lengths from 5.6 to 8.8 nm for PbPc and from 6.9 to 13.8 nm for C70 to enhance the power conversion efficiency (PCE) of the planar heterojunction OPVs composed of PbPc and C70 from 1.4 to 2.3%. The quasi-epitaxy model is proposed to explain the multilayer epitaxy.
