EFFECT OF EXPOSURE TO LOW TEMPERATURE ON BLOOD CLEARANCE OF CARBON AND BACTERIA IN MICE

摘要

Mice housed at 5 C clear carbon from the blood more slowly than animals at 25 C but those in the cold clear at the same rate even after exposures of 2, 18 or 72 hours prior to the test. Bacteria are also "cleared" uniformly at the two. temperatures when a highly virulent strain of Salmonella typhimurium is injected intravenously but not when one of low virulence is used. Here, mice at 25 C show a steady decline in bacteremic level but not those at 5° C. The LD50 dose of bacteria via the intravenous route is higher than the intraperitoneal dose with strains of each virulence in mice kept at 25 C but it is clearly lower for the mice housed at 5° C. In line with these findings is the observation that exposure to 5 C for 8 hours post infection followed by 16 hours at 25°C yields mortalities similar to continuous exposure to 25 C and vice versa.