Nitric oxide activates Ca2+-activated K+ channels in cultured bovine adrenal chromaffin cells.
The effects of sodium nitroprusside (SNP) on Ca2+-dependent K+ (KCa) channels in cultured bovine adrenal chromaffin cells were investigated using single channel recording patch-clamp techniques. KCa channels were activated by application of 100 microM SNP to the extracellular side of cell-attached patches. Methylene blue (300 microM), an inhibitor of soluble guanylate cyclase, or H-8 (1 microM), a protein kinase inhibitor with relative specificity for cGMP-dependent protein kinase, diminished but did not completely abolish the SNP-induced KCa channel activation. Diethylamine/NO complex (DEA/NO), an NO donor, also activated KCa channels in cell-attached patches. Furthermore, application of 100 microM SNP or 100 nM DEA/NO to the intracellular surface of excised inside-out patches also activated KCa channels in the bath solution which contained 1 microM Ca2+. These results indicate that SNP is capable of activating the KCa channel via cGMP-dependent and -independent mechanisms. These studies demonstrate that NO may serve as an important regulatory mechanism for catecholamine secretion in chromaffin cells via the activation of KCa channels.
Chen
C H
CH
Department of Nutrition, School of Medicine, University of Tokushima, Japan.
Houchi
H
H
Ohnaka
M
M
Sakamoto
S
S
Niwa
Y
Y
Nakaya
Y
Y
D000313:Adrenal Medulla / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002395:Catecholamines / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000187:drug effects / Q000378:metabolism*; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors; D006834:Hydrazines / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D008751:Methylene Blue / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D009589:Nitrogen Oxides; D009599:Nitroprusside / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology
D002395:Catecholamines; D004791:Enzyme Inhibitors; D006834:Hydrazines; D007546:Isoquinolines; D009589:Nitrogen Oxides; D015221:Potassium Channels; D009599:Nitroprusside; D009569:Nitric Oxide; C053177:N-(2-(methylamino)ethyl)-5-isoquinolinesulfonamide; C084012:1,1-diethyl-2-hydroxy-2-nitrosohydrazine; D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase; D002118:Calcium; D008751:Methylene Blue