title: Mechanical strain suppresses inducible nitric-oxide synthase in cardiac myocytes.
abstract: We investigated the effects of precisely controlled mechanical strain on nitric-oxide synthase activity in cultured neonatal rat cardiac myocytes. Incubation of cardiac myocytes for 24 h with 4 ng/ml interleukin-1beta and 100 units/ml interferon-gamma stimulated an increase in nitric oxide production, inducible nitric-oxide synthase (iNOS) mRNA, and iNOS protein. Mechanical strain suppressed nitric oxide production, iNOS mRNA, and iNOS protein stimulated by cytokines in an amplitude-dependent manner. Losartan (1 microM), an angiotensin II type 1 receptor antagonist, weakly inhibited the effect of strain, suggesting that paracrine angiotensin II is not the mediator of the strain effect. In addition, cycloheximide (10 microM), a protein synthesis inhibitor, inhibited the effect of strain by 46%. Transforming growth factor-beta (1 ng/ml) suppressed iNOS mRNA expression, but anti-transforming growth factor-beta antibody (30 microg/ml) did not block the effect of strain. In contrast, staurosporine (100 nM; a nonselective protein kinase inhibitor), calphostin C (1 microM; a selective protein kinase C inhibitor), and pretreatment with phorbol 12-myristate 13-acetate abolished the effect of strain. Genistein (100 microM), a tyrosine kinase inhibitor, partially inhibited the effect of strain. Thus, cyclic mechanical deformation suppresses cytokine-induced iNOS expression in cardiac myocytes, and this effect is mediated at least partially via activation of protein kinase C.
authors.affiliation: Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: K
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Q N
authors.initials: QN
authors.lastname: Dang
authors.forename: R A
authors.initials: RA
authors.lastname: Kelly
authors.forename: R T
authors.initials: RT
authors.lastname: Lee
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D006352:Heart Ventricles / Q000166:cytology; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D009206:Myocardium / Q000201:enzymology*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D011493:Protein Kinase C / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin / Q000502:physiology; D013314:Stress, Mechanical; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000502:physiology
chemical_list: D007375:Interleukin-1; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin; D016212:Transforming Growth Factor beta; D007371:Interferon-gamma; D003513:Cycloheximide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate