放射损伤、烧伤和放烧复合伤心功能的早期改变

Early functional changes of the heart after radiation, burn or combined radiation-burn injury in rats

采用离体工作心脏装置(isolated working heart preparation,IWHP)研究放烧复合伤对心脏功能的影响。实验大鼠分成对照组(C)、烧伤组(B)、放射损伤组(R)和放烧复合伤组(RB)。经^(60)Co γ线照射和/或5KW溴钨灯光辐射致放射伤和/或30％TBSA Ⅲ度烧伤,伤后不补液、测定伤后1、3、8、16和24h离体灌流心脏的LVSP、±dp/dtmax、CO、HR、CF和AP,并计算心脏干湿重比Rw。RB组LVSP、±dp/dtmax、CO和AP,伤后8h降低最为明显(P<0.05),分别为C组的79.8％、63.7％、59.4％、88.0％,且均较B组下降为轻,较R组重。CF和Rw无明显组间差异。结果提示:放烧复合伤早期已有心肌固有收缩能力(intrinsic contractility)的抑制,该抑制作用在伤后24h时内表现为加重-恢复过程,且抑制程度较单烧伤为轻。

The early functional changes of the heart after radiation, burn or combined radiation-burn injury were studied with an isolated working heart preparation of rats. The animals were randomized into the control group (C), the burn injury group (B) inflicted with 30% TB-SA full thickness burns from a 5 kw bromine-tungsten lamp, the radiation injury group (R) inflicted with total body irradiation of 6 Gy from a 'Co source and the combined radiation-burn injury group (RB) receiving both of the injuries. No treatment was administered after injury. Left ventricular systolic pressure (LVSP). maximum of LV pressure development ( ± dp/ dtmax), heart rate (HR), cardiac output (CO), coronary flow (CF), aortic pressure (A.P) and ratio of dry/wet myocardial weight (Rw) of the perfused isolated heart were determined in the 1st, 3rd, 8th, 16th and 24th hour after injury. It was found that LVSP, ±dp/dtmax, CO and AP were decreased in RB especially in the 8th hour after injury ( P <0. 05 as compared with those of C). After the 8th hour, different degrees of recovery were observed. The decrease of these parameters was less intense in RB than in B but more intense in RB than in R. HR, CF and Rw showed no significant difference between RB and C. The findings suggest that combined radiation-burn injury results in a suppression on the intrinsic contractility of the myocardium in the early stage after injury and myocardial suppression from burn injury is more severe than that from the combined injury throughout the whole period of observation.