title: Endothelin-3 attenuates the cyclic GMP responses to C-type natriuretic peptide in cultured mouse astrocytes.
abstract: The effect of endothelin-3 (ET-3) on cyclic GMP (cGMP) responses to C-type natriuretic peptide (CNP) was studied in primary cultures of mouse astrocytes. Attenuation of CNP-stimulated cGMP formation by ET-3 was time-dependent, with maximum inhibition achieved at 30 min of preincubation. ET-3 suppressed cGMP production in response to 10 nM CNP in a dose-dependent fashion, with an IC50 of 0.04 nM and a maximal inhibitory concentration of 1 microM, which led to a 66% reduction of the cGMP increment from 45.0 +/- 4.2 pmol/mg protein to 15.4 +/- 2.6 pmol/mg protein. ET-1, ET-2, and ET-3 were equipotent in suppressing the CNP-induced cGMP response, suggesting that this effect was mediated by ETB receptors. Staurosporine, Ro 31-8220, calcium-free medium, nifedipine, verapamil, lanthanum, thapsigargin, BAPTA, W7, calmidazolium, U-73122, neomycin, quinacrine, wortmannin, herbimycin-A, okadaic acid, and sodium orthovanadate failed to block the effect of ET-3. Cycloheximide (100 microM), however, partially but significantly reversed the inhibitory effect of ET-3 on CNP-induced cGMP from 48.2 to 73.3% of the control value. The results support the premise that ET-3 and CNP interact within the central nervous system. The data also suggest that cGMP accumulation in mouse astrocytes is mediated by activation of certain kinases through as yet undefined mechanisms and not by protein kinase C, increased intracellular calcium, or other second messenger pathways such as phospholipases A2, C, D, tyrosine kinase, or protein phosphatases.
authors.affiliation: Department of Medicine, Faculty of Medicine, Chinese University of Hong Kong, Shatin, NT, Hong Kong.
authors.forename: V T
authors.initials: VT
authors.lastname: Yeung
authors.forename: S K
authors.initials: SK
authors.lastname: Ho
authors.forename: D S
authors.initials: DS
authors.lastname: Tsang
authors.forename: M G
authors.initials: MG
authors.lastname: Nicholls
authors.forename: C S
authors.initials: CS
authors.lastname: Cockram
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000032:analysis / Q000378:metabolism; D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D009320:Atrial Natriuretic Factor / Q000494:pharmacology; D001667:Binding, Competitive / Q000502:physiology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured / Q000187:drug effects / Q000201:enzymology; D006152:Cyclic GMP / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D019334:Endothelin-3 / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D051379:Mice; D020098:Natriuretic Peptide, C-Type; D010739:Phospholipase D / Q000378:metabolism; D010741:Phospholipases A / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000494:pharmacology*; D019311:Staurosporine / Q000494:pharmacology; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D019334:Endothelin-3; D004791:Enzyme Inhibitors; D007211:Indoles; D007476:Ionophores; D011500:Protein Synthesis Inhibitors; D011506:Proteins; D020098:Natriuretic Peptide, C-Type; D000246:Adenosine Diphosphate Ribose; D000001:Calcimycin; D009320:Atrial Natriuretic Factor; D003513:Cycloheximide; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D010741:Phospholipases A; D010749:Phosphoprotein Phosphatases; D010738:Type C Phospholipases; D010739:Phospholipase D; D006152:Cyclic GMP; D019311:Staurosporine; D002118:Calcium; C064758:Ro 31-8220