title: Effects of modulation of nitric oxide on rat diaphragm isotonic contractility during hypoxia.
abstract: Nitric oxide (NO) is essential for optimal myofilament function of the rat diaphragm in vitro during active shortening. Little is known about the role of NO in muscle contraction under hypoxic conditions. Hypoxia might increase the NO synthase (NOS) activity within the rat diaphragm. We hypothesized that NO plays a protective role in isotonic contractile and fatigue properties during hypoxia in vitro. The effects of the NOS inhibitor N(G)-monomethyl-l-arginine (l-NMMA), the NO scavenger hemoglobin, and the NO donor spermine NONOate on shortening velocity, power generation, and isotonic fatigability during hypoxia were evaluated (Po(2) approximately 7 kPa). l-NMMA and hemoglobin slowed the shortening velocity, depressed power generation, and increased isotonic fatigability during hypoxia. The effects of l-NMMA were prevented by coadministration with the NOS substrate l-arginine. Spermine NONOate did not alter isotonic contractile and fatigue properties during hypoxia. These results indicate that endogenous NO is needed for optimal muscle contraction of the rat diaphragm in vitro during hypoxia.
authors.affiliation: Department of Pulmonary Diseases, University Medical Centre Nijmegen, The Netherlands.
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Zhu
authors.forename: Leo M A
authors.initials: LM
authors.lastname: Heunks
authors.forename: Herwin A
authors.initials: HA
authors.lastname: Machiels
authors.forename: Leo
authors.initials: L
authors.lastname: Ennen
authors.forename: P N Richard
authors.initials: PN
authors.lastname: Dekhuijzen
mesh_terms: D000818:Animals; D003964:Diaphragm / Q000503:physiopathology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006454:Hemoglobins / Q000494:pharmacology; D000860:Hypoxia / Q000503:physiopathology*; D066298:In Vitro Techniques; D007551:Isotonic Contraction / Q000187:drug effects; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009589:Nitrogen Oxides; D010807:Physical Endurance; D051381:Rats; D017208:Rats, Wistar; D013096:Spermine / Q000031:analogs & derivatives* / Q000494:pharmacology; D013997:Time Factors; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D006454:Hemoglobins; D020030:Nitric Oxide Donors; D009589:Nitrogen Oxides; C091861:spermine nitric oxide complex; D019323:omega-N-Methylarginine; D013096:Spermine; D009569:Nitric Oxide