Methods (1)Eighty male Sprague-Dawley (SD) rats were randomly divided into 4 groups (n=80): sham-scald group; burns with no rehydration group; burns with hypotonic sodium pyruvate-oral rehydration solution group and burns with hypotonic sodium citrate-oral rehydration solution group. Each group had 20 rats. The osmolarity of sodium pyruvate-oral rehydration solution and sodium citrate-oral rehydration solution were respectively about 247 mOsm/L and 245 mOsm/L. Except for the sham-scald group, the rats were subjected to 50% total body surface area(TBSA) third-degree burns by immersing the back of the backpart for 15 s, both lower extremities for 15 s and the abdomen for 8 s in 96 ℃ water. sham-scald rats were immersed in 37 ℃ water instead. Immediately after scalding, rehydrated animals received the oral rehydration solution treatment through the gavage. According to the Parkland formula, the total amount of crystalloids was 4mL/ kg × 1% TBSA. One half of volume was infused during the first 8 hours, the rest during the following 16 hours after burns. All rats received the oral rehydration solution treatment through the gavage in every 0.5 h strictly according to the coculation. The rats in the sham-scald group were treated with free drinking water and rats in burns with no rehydration group were not given with oral rehydration solution. Hemodynamic parameters [mean arterial pressure(MAP), cardiac outcome (CO), dp/dtmax, systemic vascular resistance (SVR)] and liver, kidney and intestinal mucosal blood perfusion were observed at 8 h and 24 h after injury. (2)Another set of 80 male SD rats in identical experimental procedures without tests was randomly assigned to sham control group; burns with no rehydration group; burns with hypotonic sodium citrate-oral rehydration solution group and burns with hypotonic sodium pyruvate-oral rehydration solution group (n=20, each group) for analyzing the survival rate at 8 h and 24 h after burn. Data were processed with one-way ANOVA, t test and Chi-square test.
Results (1)The hemodynamic parameters (MAP, CO, dp/dtmax, SVR) were significantly different at 8 h and 24 h after burn, there were significant differences (with P values below 0.05). Compared with that in burns with no rehydration solution group, the hemodynamic parameters (MAP, CO, dp/dtmax) of other 3 groups were higher, there were significant differences (with P values below 0.05). The hemodynamic parameters in burns with no rehydration solution group continued to decline until death.MAP, CO and dp/dtmax were higher in burns with hypotonic sodium pyruvate-oral rehydration solution group[(96.34±8.23) mmHg, (1.68±0.08) L/min and (720.46±61.37) mmHg/s] than that in burns with hypotonic sodium citrate-oral rehydration solution group [(75.35±7.63) mmHg, (0.97±0.05) L/min and (670.87±70.61) mmHg/s] at 8 h postburn; the differences were statistically significant (t=5.125, 2.375, 2.412, with P values below 0.05). MAP, CO and dp/dtmax were also higher in burns with hypotonic sodium pyruvate-oral rehydration solution group [(112.78±9.32) mmHg, (1.89±0.11) L/min and (953.42±74.18) mmHg/s] than that in burns with hypotonic sodium citrate-oral rehydration solution group [(93.12±10.22) mmHg, (1.13±0.09) L/min and (750.81± 65.72) mmHg/s] at 24 h postburn and the differences were statistically significant(t=5.127, 2.641, 2.981, with P values below 0.05). SVR was lower in burns with hypotonic sodium pyruvate-oral rehydration solution group [(4088.03±271.83), (3256.83±222.58) dyn·s·cm-5] than that in burns with hypotonic sodium citrate-oral rehydration solution group [(4643.17±263.72), (4305.15±230.17) dyn·s·cm-5] at 8 h and 24 h time points postburn and the differences were statistically significant (t=5.387, 4.213, with P values below 0.05). The levels of tissue blood flows (hepatic, renal and intestinal mucosa) in rats subjected to scald dropped sharply after burns, which grew to a higher level in burns with hypotonic sodium citrate-oral rehydration solution group and burns with hypotonic sodium pyruvate-oral rehydration solution group than that in the burns with no rehydration group at 8 h and 24 h postburn; the differences were statistically significant (with P values below 0.05). The levels of tissue blood flows (hepatic, renal and intestinal mucosa) were higher in burns with hypotonic sodium pyruvate-oral rehydration solution group [(225.4±28.6), (337±25.8), (68.7±10.7) BPU] than that in burns with hypotonic sodium citrate-oral rehydration solution group [(176.5±11.4), (179±19.7), (47.3±4.9) BPU] at 8 h postburn; the differences were statistically significant (t=0.168, 2.462, 2.432, with P values below 0.05). The levels of tissue blood flows (hepatic, renal and intestinal mucosa) in burns with hypotonic sodium pyruvate-oral rehydration solution group [(272.78±35.2), (319±20.1), (49.4±3.1) BPU] were higher than that in burns with hypotonic sodium citrate-oral rehydration solution group [(152.8±14.1), (128±12.7), (35.7±4.7) BPU] at 24 h postburn; the differences were statistically significant (t=3.163, 3.428, 2.314, with P values below 0.05). (2)The 24-hour survival rates of burns with hypotonic sodium pyruvate-oral rehydration solution group and burns with hypotonic sodium citrate-oral rehydration solution group were both significantly higher than the rate of the burns with no rehydration group (with P values below 0.05); the survival rate of burns with hypotonic sodium pyruvate-oral rehydration solution group (40.0%) was also significantly higher than that in the hypotonic sodium citrate-oral rehydration solution group (20.0%) and the difference was statistically significant (χ2=4.113, P=0.038).