title: H2S induced hypometabolism in mice is missing in sedated sheep.
abstract: On the basis of studies performed in mice that showed H(2)S inhalation decreasing dramatically the metabolic rate, H(2)S was proposed as a means of protecting vital organs from traumatic or ischemic episodes in humans. Hypoxia has in fact also long been shown to induce hypometabolism. However, this effect is observed solely in small-sized animals with high VO2 kg(-1), and not in large mammals. Thus, extrapolating the hypometabolic effect of H(2)S to large mammals is questionable and could be potentially dangerous. We measured metabolism in conscious mice (24 g) exposed to H(2)S (60 ppm) at an ambient temperature of 23-24 degrees C. H(2)S caused a rapid and large (50%) drop in gas exchange rate, which occurred independently of the change in body temperature. The metabolic response occurred within less than 3 min. In contrast, sheep, sedated with ketamine and weighing 74 kg did not exhibit any decrease in metabolic rate during a similar challenge at an ambient temperature of 22 degrees C. While a part of H(2)S induced hypometabolism in the mice is related to the reduction in activity, we speculate that the difference between sheep and mice may rely on the nature and the characteristics of the relationship between basal metabolic rate and body weight thus on the different mechanisms controlling resting metabolic rate according to body mass. Therefore, the proposed use of H(2)S administration as a way of protecting vital organs should be reconsidered in view of the lack of hypometabolic effect in a large sedated mammal and of H(2)S established toxicity.
authors.affiliation: Penn State Heart & Vascular Institute, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States. phaouzi@hmc.psu.edu
authors.forename: Philippe
authors.initials: P
authors.lastname: Haouzi
authors.forename: Véronique
authors.initials: V
authors.lastname: Notet
authors.forename: Bruno
authors.initials: B
authors.lastname: Chenuel
authors.forename: Bernard
authors.initials: B
authors.lastname: Chalon
authors.forename: Isabelle
authors.initials: I
authors.lastname: Sponne
authors.forename: Virginie
authors.initials: V
authors.lastname: Ogier
authors.forename: Bernard
authors.initials: B
authors.lastname: Bihain
mesh_terms: D000393:Air Pollutants / Q000633:toxicity*; D000818:Animals; D001273:Atmosphere Exposure Chambers; D001831:Body Temperature / Q000187:drug effects; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D006862:Hydrogen Sulfide / Q000633:toxicity*; D006993:Hypnotics and Sedatives / Q000494:pharmacology; D007700:Kinetics; D008660:Metabolism / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D010101:Oxygen Consumption / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012756:Sheep; D013045:Species Specificity
chemical_list: D000393:Air Pollutants; D006993:Hypnotics and Sedatives; D002245:Carbon Dioxide; D006862:Hydrogen Sulfide