Background-The potential biological significance of hydrogen sulfide (H 2 S) has attracted growing interest in recent years. The aim of this study was to characterize a novel, water-soluble, slow-releasing H 2 S compound [morpholin-4-ium 4 methoxyphenyl(morpholino) phosphinodithioate (GYY4137)] and evaluate its use as a tool to investigate the cardiovascular biology of this gas. Methods and Results-The acute vasorelaxant effect of drugs was assessed in rat aortic rings and perfused rat kidney in vitro and in the anesthetized rat in vivo. The chronic effect of GYY4137 on blood pressure in normotensive and spontaneously hypertensive rats was determined by tail-cuff plethysmography. GYY4137 released H 2 S slowly both in aqueous solution in vitro and after intravenous or intraperitoneal administration in anesthetized rats in vivo. GYY4137 caused a slow relaxation of rat aortic rings and dilated the perfused rat renal vasculature by opening vascular smooth muscle K ATP channels. GYY4137 did not affect rat heart rate or force of contraction in vitro. GYY4137 exhibited antihypertensive activity as evidenced by ability to reduce N G -nitro-L-arginine methyl ester-evoked hypertension in the anesthetized rat and after chronic (14-day) administration in spontaneously hypertensive rats. Conclusions-These results identify GYY4137 as a slow-releasing H 2 S compound with vasodilator and antihypertensive activity. GYY4137 is likely to prove useful in the study of the many and varied biological effects of H 2 S. GYY4137 may also prove of therapeutic value in cardiovascular disease.

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A planar W-band monopulse antenna array is designed based on the substrate integrated waveguide (SIW) technology. The sum-difference comparator, 16-way divider and 32 32 slot array antenna are all integrated on a single dielectric substrate in the compact layout through the low-cost PCB process. Such a substrate integrated monopulse array is able to operate over 93 96 GHz with narrow-beam and high-gain. The maximal gain is measured to be 25.8 dBi, while the maximal null-depth is measured to be 43.7 dB. This SIW monopulse antenna not only has advantages of low-cost, light, easy-fabrication, etc., but also has good performance validated by measurements. It presents an excellent candidate for W-band directional-finding systems.Index Terms-Monopulse antenna array, substrate integrated circuits (SICs), substrate integrated waveguide (SIW), W-band.