title: High perfusate PO2 impairs thermosensitivity of hypothalamic thermosensitive neurons in slice preparations.
abstract: The thermosensitivity of neurons in the preoptic area (POA) of guinea pigs was examined in slice preparations during perfusion with artificial cerebrospinal fluid (ACSF) gassed with 95% O2/5% CO2 (95% O2-ACSF) or 21% O2/5% CO2/74% N2 (21% O2-ACSF). Perfusate PO2, PCO2, and pH of 95% O2-ACSF measured in the incubation chamber were, respectively, 402.9 mmHg, 39.1 mmHg, and 7.38; those of 21% O2-ACSF were 154.0 mmHg, 33.1 mmHg, and 7.41. All the thermosensitive neurons (n = 6) originally identified during perfusion with 95% O2-ACSF also exhibited their thermosensitivity when examined again in 21% O2-ACSF. However, 63% of the thermosensitive neurons (n = 8) originally identified with 21% O2-ACSF lost their thermosensitivity in 95% O2-ACSF. The addition of superoxide dismutase to 95% O2-ACSF prevented the loss of thermosensitivity in 88% of the neurons (n = 8). These results suggest that oxygen toxicity due to free radical formation may account for the impairment of neuronal thermosensitivity in 95% O2-ACSF.
authors.affiliation: Department of Physiology and Biophysics, University of Tennessee, Memphis 38163.
authors.forename: M
authors.initials: M
authors.lastname: Shibata
authors.forename: C M
authors.initials: CM
authors.lastname: Blatteis
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000187:drug effects*; D002245:Carbon Dioxide / Q000494:pharmacology; D006168:Guinea Pigs; D006863:Hydrogen-Ion Concentration; D007031:Hypothalamus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010100:Oxygen / Q000494:pharmacology*; D011301:Preoptic Area / Q000187:drug effects / Q000502:physiology; D013482:Superoxide Dismutase / Q000494:pharmacology
chemical_list: D002245:Carbon Dioxide; D013482:Superoxide Dismutase; D010100:Oxygen