Activation of purinergic p2y2 receptors inhibits inducible no
synthase in cultured rat mesangial cells.
Mohaupt, Markus G., Tina Fischer, Jr.g Schwbel, R. Bernd Sterzel,
Eckhard Schulze-Lohoff.
Nephrologisches Labor, Medizinische Klinik IV, Universitt Erlangen
-Nrnberg, 91054 Erlangen, Germany
APStracts 5:0076F, 1998.
Cytokine-induced nitric oxide (NO) is produced upon glomerular
inflammation. Glomerular injury and thrombocyte aggregation result in
the release of nucleotides which may regulate induced NO synthesis in
cultured rat mesangial cells (MCs). ATP (10-3M) inhibited 24hr
nitrite production induced by lipopolysaccharide (LPS, 10
g/ml)/interferon-( (IFN-(, 100 U/ml) by 48.2 6.3% as well as
induction of iNOS protein and mRNA. Also coincubation with either 10
-4 M of UTP, ATP, or ATP(S inhibited LPS/IFN-(-induced nitrite
production by 29.9 5.8, 36.4(4.3 and 50.3 6.5%, respectively,
indicating involvement of purinergic P2Y2 receptors. Correspondingly,
cultured MCs expressed P2Y2 receptor mRNA. Agonists for other
purinergic receptors ((,-methylene-ATP, 3-O-[4-benzoyl]-benzoyl-ATP,
2-methylthio-ATP, ADP, UDP, adenosine) were ineffective. Treatment
with the protein kinase C activator phorbol 12-myristate 13-acetate
(PMA, 10-8M) reproduced the inhibitory effect of ATP on iNOS protein
expression and nitrite inhibition (by 46.610.4%). The effect of ATP
or PMA was reversed by the PKC-inhibitors Ro31-8220 (10-8M) and H7
(10-5M), indicating that suppression of iNOS is mediated via
activation of PKC through stimulated P2Y2 receptors. In conclusion,
the release of purine mediators may play a critical role for iNOS
expression and synthesis of NO during glomerular inflammatory
disorders.
Received 11 December 1997; accepted in final form 18 March 1998.
APS Manuscript Number F391-7.
Article publication pending Am. J. Physiol. (Renal Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 24 April 1998