title: Role of transsarcolemmal Ca2+ entry in the negative inotropic effect of nitrous oxide in isolated ferret myocardium.
abstract: The purpose of this study was to investigate the effects of nitrous oxide (N2O) on transsarcolemmal calcium influx in isolated ferret right ventricular myocardium. Using a range of loading conditions, papillary muscles were equilibrated in 50% nitrogen (N2) or 50% N2O in oxygen in the presence and absence of ryanodine, a specific inhibitor of calcium release from the sarcoplasmic reticulum. After equilibration in 50% N2O or 50% N2 in oxygen, peak developed force, peak isotonic shortening, and maximal unloaded velocity of shortening were compared in the presence and absence of 10(-6) M ryanodine. Fifty percent N2O caused a significant reduction in contractility in control conditions and a further significant reduction in contractile variables in the presence of 10(-6) M ryanodine. We conclude that at least part of the negative inotropic effect of N2O is due to an inhibition of transsarcolemmal calcium influx.
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, MN 55905.
authors.forename: E G
authors.initials: EG
authors.lastname: Carton
authors.forename: P R
authors.initials: PR
authors.lastname: Housmans
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D003864:Depression, Chemical; D005289:Ferrets; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology; D009584:Nitrogen / Q000494:pharmacology; D009609:Nitrous Oxide / Q000494:pharmacology*; D010100:Oxygen / Q000494:pharmacology; D010210:Papillary Muscles / Q000187:drug effects / Q000378:metabolism; D012433:Ryanodine / Q000494:pharmacology; D012508:Sarcolemma / Q000187:drug effects / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism
chemical_list: D012433:Ryanodine; D009609:Nitrous Oxide; D009584:Nitrogen; D010100:Oxygen; D002118:Calcium