title: Role of nitric oxide and cGMP in human septic serum-induced depression of cardiac myocyte contractility.
abstract: Previous studies have demonstrated the existence of a circulating myocardial depressant substance during human septic shock. We have recently identified this substance as a synergistic combination of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta). This study utilized an in vitro cardiac myocyte assay to evaluate the potential mechanistic role of nitric oxide (NO) and cGMP in depression of myocyte contractility induced by TNF-alpha, IL-1beta, TNF-alpha + IL-1beta (at low concentrations), and human septic shock serum (HSS). TNF-alpha, IL-1beta, TNF-alpha + IL-1beta, and each of 5 sera from patients with acute septic shock caused depression of both maximum extent and peak velocity of cardiac myocyte shortening and an increase in intracellular cGMP concentration during 30 min of exposure (minimum P < 0.01). NO synthetase (NOS) and guanylate cyclase inhibitors such as N-methyl-L-arginine (L-NMA) and methylene blue prevented these effects; an excess of L-arginine with L-NMA restored them (minimum P < 0.01). In contrast, D-arginine failed to reestablish cytokine-induced myocyte depression and cGMP accumulation prevented by L-NMA. Exposure of myocytes to TNF-alpha, IL-1beta, or TNF-alpha + IL-1beta produced a concentration-dependent increase in intracellular cGMP that paralleled the depression of cardiac myocyte contractility (minimum P < 0.001). In addition, TNF-alpha, IL-1beta, TNF-alpha + IL-1beta, or HSS application to cardiac myocytes resulted in increased NO gas generation, which was inhibited by L-NMA (minimum P < 0.01). Furthermore, unstimulated cardiac myocytes were shown to harbor constitutive but not inducible NOS activity. These data suggest that the sequential generation of NO by a constitutive NOS and cGMP by guanylate cyclase represents an important mechanism of cardiac myocyte depression by TNF-alpha, IL-1beta, TNF-alpha + IL-1beta, and the myocardial depressant substance(s) of septic shock.
authors.affiliation: Section of Critical Care Medicine, Department of Medicine, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612, USA.
authors.forename: A
authors.initials: A
authors.lastname: Kumar
authors.forename: R
authors.initials: R
authors.lastname: Brar
authors.forename: P
authors.initials: P
authors.lastname: Wang
authors.forename: L
authors.initials: L
authors.lastname: Dee
authors.forename: G
authors.initials: G
authors.lastname: Skorupa
authors.forename: F
authors.initials: F
authors.lastname: Khadour
authors.forename: R
authors.initials: R
authors.lastname: Schulz
authors.forename: J E
authors.initials: JE
authors.lastname: Parrillo
mesh_terms: D000818:Animals; D001120:Arginine / Q000494:pharmacology; D001790:Blood Physiological Phenomena; D006152:Cyclic GMP / Q000502:physiology*; D004338:Drug Combinations; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D008751:Methylene Blue / Q000494:pharmacology; D009200:Myocardial Contraction / Q000502:physiology*; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D009712:Nucleotides, Cyclic / Q000378:metabolism; D051381:Rats; D012772:Shock, Septic / Q000097:blood*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D004338:Drug Combinations; D004791:Enzyme Inhibitors; D007375:Interleukin-1; D009712:Nucleotides, Cyclic; D014409:Tumor Necrosis Factor-alpha; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D001120:Arginine; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D006152:Cyclic GMP; D008751:Methylene Blue