cGMP/Protein Kinase G-Dependent Inhibition of N-Type Ca2+Channels Induced by Nitric Oxide in Human Neuroblastoma IMR32 Cells

• DOI: 10.1523/jneurosci.22-17-07485.2002
• Publication Date: 2018-04-13T22:27:17Z
• Authors: Marcello D'Ascenzo; Giovanni Martinotti; Gian Battista Azzena; Claudio Grassi
• Keywords: Sodium nitroprusside; cGMP-dependent protein kinase

Although data from our laboratory and others suggest that nitric oxide (NO) exerts an overall inhibitory action on high-voltage-activated Ca2+ channels, conflicting observations have been reported regarding its effects N-type channels. We performed whole-cell cell-attached patch-clamp recordings in IMR32 cells to clarify the functional role of NO modulation N channels human neuronal cells. During depolarizing steps +10 mV V(h) = -90 mV, donor, sodium nitroprusside (SNP; 200 microm), reduced macroscopic currents by 34% (p < 0.01). The magnitude inhibition was similar at all voltages tested (range, -40 +50 mV). No significant observed when SNP applied together with scavenger, 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide potassium salt (300 or after cell treatment guanylate cyclase inhibitor, 1H-[1,2,4] oxadiazole [4,3-a] quinoxalin-1-one (10 microm). 8-bromoguanosine-cGMP (8-Br-cGMP) (400 microm) mimicked SNP, reducing Ba2+ 37% 0.001). Cell protein kinase G (PKG) inhibitor KT5823 (1 guanosine 3',5'-cyclic monophosphorothioate, 8-(4-chloro-phenylthio)-Rp-isomer, triethylammonium (20 virtually abolished 8-Br-cGMP. At single-channel level, 8-Br-cGMP channel open probability 59% increased both mean shut time null sweep probability, but it had no conductance, time, latency first openings. These inhibits N-channel gating through cGMP PKG. consequent decrease influx these may affect different functions, including neurotransmitter release.