title: Seasonal changes in blood oxygen transport and acid-base status in the tegu lizard, Tupinambis merianae.
abstract: Oxygen-binding properties, blood gases, and acid-base parameters were studied in tegu lizards, Tupinambis merianae, at different seasons and temperatures. Independent of temperature and pH, blood oxygen affinity was higher in dormant lizards than in those active during the summer. Haematocrit (Hct) and hemoglobin content ([Hb]) were greater in active lizards resulting in a higher oxygen-carrying capacity. Nucleoside triphosphate content ([NTP]) was reduced during dormancy, but the ratio between [NTP] and [Hb] remained unchanged. Dormancy was accompanied by an increase in plasma bicarbonate ([HCO-(3)]pl) and an elevation of arterial CO2 partial pressure (PaCO2) and CO2 content in the plasma (CplCO2). These changes in acid-base parameters persist over a broad range of body temperatures. In vivo, arterial O2 partial pressure (PaO2) and O2 content (CaO2) were not affected by season and tended to increase with temperature. Arterial pH (pHa) of dormant animals is reduced compared to active lizards at body temperatures below 15 degrees C, while no significant difference was noticed at higher temperatures.
authors.affiliation: Departamento de Zoologia, Universidade Estadual Paulista, Caixa Postal 199, 13500-970 Rio Claro, SP, Brazil. denis@rc.unesp.br
authors.forename: Denis V
authors.initials: DV
authors.lastname: Andrade
authors.forename: Simone P
authors.initials: SP
authors.lastname: Brito
authors.forename: Luís Felipe
authors.initials: LF
authors.lastname: Toledo
authors.forename: Augusto S
authors.initials: AS
authors.lastname: Abe
mesh_terms: D000136:Acid-Base Equilibrium / Q000502:physiology*; D000818:Animals; D001639:Bicarbonates / Q000097:blood; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000378:metabolism; D006400:Hematocrit / Q000379:methods; D006454:Hemoglobins / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008116:Lizards; D043583:Nucleoside-Triphosphatase / Q000378:metabolism; D010100:Oxygen / Q000097:blood*; D010313:Partial Pressure; D015657:Respiratory Transport / Q000502:physiology*; D012621:Seasons; D013696:Temperature
chemical_list: D001639:Bicarbonates; D006454:Hemoglobins; D002245:Carbon Dioxide; D043583:Nucleoside-Triphosphatase; D010100:Oxygen