Inducible nitric oxide synthase in the myocard.
Recognition of significance of nitric oxide synthases (NOS) in cardiovascular regulations has led to intensive research and development of therapies focused on NOS as potential therapeutic targets. However, the NOS isoform profile of cardiac tissue and subcellular localization of NOS isoforms remain a matter of debate. The aim of this study was to investigate the localization of an inducible NOS isoform (NOS2) in cardiomyocytes. Employing a novel immunocytochemical technique of a catalyzed reporter deposition system with tyramide and electron microscopical immunocytochemistry complemented with Western blotting and RT-PCR, we detected NOS2 both in rat neonatal and adult cultured cardiomyocytes and in the normal myocard of adult rats as well as in the human myocard of patients with dilative cardiomyopathy. NOS2 was targeted predominantly to a particulate component of the cardiomyocyte--along contractile fibers, in the plasma membrane including T-tubules, as well as in the nuclear envelope, mitochondria and Golgi complex. Our results point to an involvement of NOS2 in maintaining cardiac homeostasis and contradict to the notion that NOS2 is expressed in cardiac tissue only in response to various physiological and pathogenic factors. NOS2 targeting to mitochondria and contractile fibers suggests a relationship of NO with contractile function and energy production in the cardiac muscle.
Franz Volhard Clinic, Medical Faculty of the Charite, Humboldt University of Berlin, Germany.
I B
IB
Buchwalow
W
W
Schulze
P
P
Karczewski
M M
MM
Kostic
G
G
Wallukat
R
R
Morwinski
E G
EG
Krause
J
J
Müller
M
M
Paul
J
J
Slezak
F C
FC
Luft
H
H
Haller
D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D002311:Cardiomyopathy, Dilated / Q000201:enzymology; D002478:Cells, Cultured; D005455:Fluorescent Antibody Technique; D006056:Golgi Apparatus / Q000201:enzymology; D006801:Humans; D016253:Microscopy, Immunoelectron; D008929:Mitochondria, Heart / Q000201:enzymology; D018485:Muscle Fibers, Skeletal / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology* / Q000648:ultrastructure; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D009685:Nuclear Envelope / Q000201:enzymology; D016133:Polymerase Chain Reaction; D051381:Rats; D017208:Rats, Wistar
C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat