体温过高对大鼠脑干听觉诱发电位和中潜伏期反应的影响

EFFECTS OF HYPERTHERMIA ON BRAINSTEM AUDITORY EVOKED POTENTIALS AND MIDDLE LATENCY RESPONSE IN RATS

目的 :探讨体温过高对大鼠脑干听觉诱发电位 (BAEP)和听觉中潜伏期反应 (MLR )的影响。方法 :诱发电位仪颅表记录大鼠BAEP和MLR ;体表物理升温法逐步升高麻醉大鼠体温 ,传感探头式数字体温计监测大鼠直肠体温 ;主要观察BAEP和MLR的波峰潜伏期 (PL)、波峰间潜伏期 (IPL)和波幅随体温升高而发生的变化及它们消失的临界体温。结果 :BAEP各波PL及Ⅰ Ⅱ、Ⅰ Ⅲ、Ⅰ ⅣIPL随体温升高 ( 3 7～ 41.5℃ )而逐步缩短 ,但当体温升高至 42℃和超过 42℃时各波PL及Ⅰ Ⅱ、Ⅰ ⅣIPL不再继续缩短 ,并略有反向延长 ;MLR各波PL和P1 P3、P2 P3IPL也随体温升高 ( 3 7～ 43℃ )而缩短。随体温升高 ,BAEP和MLR波幅的主要表现为降低 ,特别是在体温升高至42℃以后。BAEP和MLR在体温 ( 4 3 .1± 0 .5)℃时出现不可逆性消失 ,且两者同步消失。结论 :体温过高对大鼠BAEP和MLR有相似的显著影响 ,体温过高至一临界值时会造成BAEP和MLR的不可逆性损害。

Aim: To study the effects of hyperthermia on brainstem auditory evoked p otentials (BAEP) and middle latency response (MLR) in rats. Methods: BAEP and MLR were recorded at the skull surface of rats. The body temperatu re of anesthetized rats increased gradually with a physical method and was detec ted by a digital thermometer inserted into the rectum. The peak latency (PL), in terpeak latency (IPL), wave amplitude and the critical body temperature at which BAEP and MLR completely lost had been observed. Results: All PL and Ⅰ-Ⅱ,Ⅰ-Ⅲ and Ⅰ-Ⅳ IPL of BAEP shortened more and more as the body t emperature increased step by step from 37℃ to 41.5℃. But all PL and Ⅰ-Ⅱ and Ⅰ-Ⅳ IPL did not shortened further and prolonged a little contrary as the bo dy temperature at 42℃ and over 42℃. All PL and P1-P3 and P2-P3 IPL of MLR a lso shortened as the body temperature increased from 37℃ to 43℃. The wave ampl itudes of BAEP and MLR decreased as the body temperature increased, especially a s the body temperature over 42℃. BAEP and MLR lost completely and synchronously at the body temperature (43.1±0.5)℃, which was not reversed as the body temp erature returning to normal by cooling. Conclusion: There were o bvious effects of hyperthermia on both BAEP and MLR in rats, and irreversible im pairments appeared at a critical body temperature.