Peripherally administered cations do not modify febrile responses induced in chickens by Escherichia coli
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Abstract:
Two experiments were conducted to investigate the effects on intramuscular injections of Escherichia coli strains B and W on rectal temperature in broiler chicks and to investigate the effects of various cations on the temperature response. In Experiment 1, 4 birds were randomly assigned to each of three treatments. Control birds received a dextrose (50 mg/100 ml) solution and treated birds received a suspension of either E. coli B or E. coli W lyophilized cells (100 mg/kg) in a volume of 2 ml/kg. Rectal temperatures were recorded before injection and thereafter every 4 hr for a period of 24 hr. In Experiment 2, 10 birds were assigned randomly to each of two treatments. Birds received intramuscularly 2 ml/kg body weight injections of either dextrose (50 mg/100 ml) solution or a suspension of E. coli B lyophilized cells (100 mg/kg) in a volume of 2 ml/kg. At 16 hr after injection, rectal temperatures were recorded and birds were divided into the following treatments with 5 birds per group. Birds previously receiving dextrose (50 mg/100 ml) were given intramuscular injections (2 ml/kg body weight) of demineralized distilled water or a 2 ml/kg injection of .5 M solution of either Na+, K+, Ca+2, or Mg+2 made from their chloride salts. Birds previously receiving E. coli B were given intramuscular injections (2 ml/kg body weight) of demineralized distilled water or an injection of a .5 M solution of either Na+, K+, Ca+2, or Mg+2. Five birds served as uninjected controls. Rectal temperatures were taken every 30 min for 90 min thereafter. In Experiment 1, intramuscular injections of E. coli B and E. coli W resulted in an initial fall in rectal temperatures of chickens followed by a rise after 4 hr that peaked at 16 hr postinjection and at 24 hr remained significantly above preinjection values. The injection of the cations Na+, K+, Ca+2, or Mg+2 in Experiment 2 did not significantly affect the febrile response produced by E. coli B.