P2X₃ Knock-Out Mice Reveal a Major Sensory Role for Urothelially Released ATP

The present study explores the possible involvement of a purinergic mechanism in mechanosensory transduction in the bladder using P2X₃ receptor knock-out (P2X₃ ⁻⁄⁻) and wild-type control (P2X₃ ⁺⁄⁺) mice. Immunohistochemistry revealed abundant nerve fibers in a suburothelial plexus in the mouse bladder that are immunoreactive to anti-P2X₃. P2X₃ -positive staining was completely absent in the subepithelial plexus of the P2X₃ ⁻⁄⁻ mice, whereas staining for calcitonin gene-related peptide and vanilloid receptor 1 receptors remained. Using a novel superfused mouse bladder–pelvic nerve preparation, we detected a release of ATP proportional to the extent of bladder distension in both P2X₃ ⁻⁄⁻ mice, whereas staining for calcitonin gene-related peptide and vanilloid receptor 1 receptors remained. Using a novel superfused mouse bladder–pelvic nerve preparation, we detected a release of ATP proportional to the extent of bladder distension in both P2X₃ ⁺⁄⁺ and P2X₃ ⁻⁄⁻ mice, although P2X₃ ⁻⁄⁻ bladder had an increased capacity compared with that of the P2X₃ ⁺⁄⁺ bladder. The activity of multifiber pelvic nerve afferents increased progressively during gradual bladder distension (at a rate of 0.1 ml/min). However, the bladder afferents from P2X₃ ⁻⁄⁻ mice showed an attenuated response to bladder distension. Mouse bladder afferents of P2X₃ ⁺⁄⁺, but not P2X₃ ⁻⁄⁻, were rapidly activated by intravesical injections of P2X agonists (ATP or α,β-methylene ATP) and subsequently showed an augmented response to bladder distension. By contrast, P2X antagonists [2′,3′-O-(2,4,6-trinitrophenyl)-ATP and pyridoxal 5-phosphate 6-azophenyl-2′,4′-disulfonic acid] and capsaicin attenuated distension-induced discharges in bladder afferents. These data strongly suggest a major sensory role for urothelially released ATP acting via P2X₃ receptors on a subpopulation of pelvic afferent fibers

Preparative Aspects of Supported Ni2P Catalysts for Reductive Upgrading of Technical Lignin to Aromatics

Supported Ni2P was evaluated as a hydrodeoxygenation (HDO) catalyst in the reductive upgrading of a soda lignin in supercritical ethanol by a hydrotalcite-derived mixed Cu-Mg-Al oxide (CuMgAlOx) catalyst. Various Ni2P catalysts were prepared by different approaches on silica, γ-alumina and a siliceous amorphous silica-alumina (ASA) supports. Calcined NiO/SiO2 precursors were impregnated with phosphate, phosphite and hypophosphite followed by reduction. With γ-alumina, the desired Ni2P could not be obtained, presumably due to the reaction of the P-source with alumina. NiO on ASA could be converted to Ni2P by addition of phosphite, preferably at a P/Ni ratio of 1. Low P/Ni ratio avoids blockage of the pores by P-oxide species remaining after reduction. By further comparison to a sol–gel prepared NiO/SiO2 and co-impregnated silica, it was established that the most active Ni2P catalyst was obtained by impregnation of NiO/SiO2 with phosphate at P/Ni = 1 and reduction at 620 °C. In combination with CuMgAlOx, more than half of soda lignin can be converted to aromatics monomers with a relatively high degree of deoxygenation and limited degree of ring hydrogenation. The co-catalyst system is more active than the separate catalysts