title: Responses of bovine lymphocytes to heat shock as modified by breed and antioxidant status.
abstract: We tested whether resistance of lymphocytes to heat stress is modified by breed, intracellular glutathione content, and extracellular antioxidants. In the first experiment, lymphocytes from Angus (Bos taurus, non-heat-tolerant), Brahman (B. indicus, heat-tolerant), and Senepol (B. taurus, heat-tolerant) heifers (12 heifers per breed) were cultured at 45 degrees C for 3 h to evaluate thermal killing, at 42 degrees C for 12 h in a 60-h phytohemagglutinin-induced proliferation test, and at 42 degrees C for 1 h to measure induction of heat shock protein 70 (HSP70). Killing at 45 degrees C was affected by breed x temperature (P < .01); the decrease in viability caused by a temperature of 45 degrees C was greater for Angus than for Brahman or Senepol. For phytohemagglutinin-stimulated lymphocytes, heating to 42 degrees C reduced [3H]thymidine incorporation equally for all breeds. Viability at the end of culture was affected (P < .001) by a breed x temperature interaction because the decrease in viability caused by culture at 42 degrees C was greatest for lymphocytes from Angus heifers. Heat shock for 1 h at 42 degrees C caused a two- to threefold increase in intracellular concentrations of HSP70, but there was no interaction of temperature with breed. In another experiment (with lymphocytes harvested from three Holstein cows), buthionine sulfoximine, a glutathione synthesis inhibitor, inhibited (P < .01) proliferation of phytohemagglutinin-stimulated lymphocytes at 38.5 and 42 degrees C. Addition of the antioxidants glutathione or thioredoxin to culture did not reduce the effects of heating to 42 degrees C on proliferation.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Animal Science, Bunda College of Agriculture, University of Malaŵi, Lilongwe.
authors.forename: L A
authors.initials: LA
authors.lastname: Kamwanja
authors.forename: C C
authors.initials: CC
authors.lastname: Chase
authors.forename: J A
authors.initials: JA
authors.lastname: Gutierrez
authors.forename: V
authors.initials: V
authors.lastname: Guerriero
authors.forename: T A
authors.initials: TA
authors.lastname: Olson
authors.forename: A C
authors.initials: AC
authors.lastname: Hammond
authors.forename: P J
authors.initials: PJ
authors.lastname: Hansen
mesh_terms: D000818:Animals; D000963:Antimetabolites / Q000494:pharmacology; D000975:Antioxidants / Q000378:metabolism*; D001947:Breeding; D019328:Buthionine Sulfoximine; D002417:Cattle / Q000097:blood* / Q000235:genetics; D002470:Cell Survival; D002478:Cells, Cultured; D005260:Female; D005978:Glutathione / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000494:pharmacology*; D006358:Hot Temperature; D008213:Lymphocyte Activation / Q000187:drug effects; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008717:Methionine Sulfoximine / Q000031:analogs & derivatives / Q000494:pharmacology; D013879:Thioredoxins / Q000494:pharmacology
chemical_list: D000963:Antimetabolites; D000975:Antioxidants; D006360:Heat-Shock Proteins; D008717:Methionine Sulfoximine; D019328:Buthionine Sulfoximine; D013879:Thioredoxins; D005978:Glutathione