The gradient heat stress impact on the convalescent core body temperature and prognosis in heatstroke rats

FU Wei; LIU Ya-nan; GENG Yan; PENG Na; LEI Yu-mei; SU Lei; TANG Zhong-zhi

Abstract：Objective To construct the gradient heat stress rat model and thus to study its influence on core body temperature ( Tc ) during heat stress and prognosis .Methods Male SPF SD rats were randomly divided into normal con-trol group, 41℃group, the 42℃group, 43℃group and 44℃group.Except for normal control group , the rats were ex-posed 39℃heat stress .The rectal thermocouple was used to measure rectal temperature as Tc , which was monitored every 10 min.When the corresponding preset temperatures were reached , the rats in the 41℃, 42℃, 43℃ and 44℃ groups were placed in ambient temperature of 25℃.The Tc was monitored within 8 h, and the survival within 72 h was also recorded.Results With varying degrees of heat stress , the Tc of rats was presented in different patterns .Biphasic rise was observed in 41℃and 42℃groups, while triphasic rise was observed in 43℃and 44℃groups.Out of heat stress, the Tc in 41℃and 42℃groups was returned to normal levels within 1 h, while low Tc was observed in 43℃and 44℃groups, and especially in 44℃group.Deaths were recorded in 43℃and 44℃groups, while significantly worse prognosis was re-vealed in 44℃group according to survival analysis (P<0.01).Conclusion Different degrees of heat stress have signi-ficant effect on Tc in rats.The higher degree of heat stress , the lower Tc is presented during the convalescence , suggesting worse prognosis .