The large conductance Ca2+ activated K+ channel (BK channel) has been considered to play an important role in the excitability and contractility of vascular smooth muscle cells. Activation of the BK channel causes the hyperpolarization and relaxation of vascular smooth muscle cells. It has been reported that fatty acids can affect the BK channel activity and its concentration is increased significantly during myocardial ischemia. These reports suggest that fatty acids may contribute to the ischemic coronary vasodilation by increasing the BK channel activity. However, the underlying mechanism of fatty acid-induced activation of the BK channel is still uncertain. In the present study, we measured the effect of fatty acids on the BK channel activity in rabbit coronary smooth muscle cells by using patch clamp method and also examined its underlying mechanism. Arachidonic acid (AA) dissolved in DMSO activated the BK channel in a dose-dependent manner (from 0.5 to 10 microM), and DMSO (0.1%) alone had no effect on the activity of the BK channel. Arachidonic acid activated BK channels in both cell-attached and inside-out patches, but the onset and recovery of this effect were slower in the cell-attached patch configuration. The BK channel activity was also increased by other fatty acids, including myristic acid, linoleic acid, palmitoleic acid and palmitic acid. Long chain fatty acids were more effective than short chain fatty acids (myristic acid), and there was no statistical difference between the effect of saturated (palmitic acid) and unsaturated fatty acids (palmitoleic acid) on the BK channel activity. The concentration of Ca2+ and Mg2+ in the bathing solution had no appreciable effects on the AA-induced increase of BK channel activity. From the above results, it may be concluded that fatty acids directly increase the BK channel activity and may contribute to the ischemic coronary vasodilatation in rabbit coronary smooth muscle cells.

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A co-planar type single chamber solid oxide fuel cell (SC-SOFC) with linearly patterned electrode structures on the same surface as the electrolyte has been fabricated by robo-dispensing method. Paste materials of NiO-SDC-Pd cermet and (La 0.7 Sr 0.3 ) 0.95 MnO 3 (LSM) were selectively deposited onto a substrate of yttria stablized zirconia (YSZ) by extrusion through a syringe nozzle. The dispensed pastes were solidified upon solvent evaporation, and the anode and the cathode were sintered at 1350 • C for 2 h and 1200 • C for 1h, respectively. We have fabricated SC-SOFCs that have a single electrode pair with varying anode-to-cathode distances and interdigitated patterned electrodes with 2, 4, and 8 multiple pairs. The electrode microstructures of the resulting cells were examined by SEM. The electrochemical performance of the SC-SOFCs was also analyzed using impedance spectroscopy and a DC source meter.

Integrated planar solid oxide fuel cell (IP-SOFC) with multilayered structure has been fabricated via directwriting process named robo-dispensing. Partially stabilized zirconia (PSZ) substrate with sufficient mechanical strength and gas permeability was utilized as a support for SOFC. The 2-cells serially integrated planar SOFC in which each cell is composed of the line-shaped electrode and electrolyte was produced The SOFC component paste materials were dispensed through cylindrical nozzle of 0.21 mm in diameter onto a moving plate that was controlled by robo-dispensing machine. The thicknesses of anode, electrolyte and cathode were 30 μm, 15 μm and 20 μm, respectively. The fabricated IP-SOFC exhibited OCV of 1.82 V and maximum power density of 35 mW.

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