Effects of different doses of dopamine on organ function of rats at early stage of severe scald

Objective To explore the effects of different doses of dopamine on organ function of rats at early stage of severe scald. Methods Thirty-two male Wistar rats aged 8 to 12 weeks were divided into sham injury (SI) group, simple resuscitation (SR) group, small dose (SD) group, and moderate dose (MD) group according to the random number table, with 8 rats in each group. After rats in the 4 groups were performed cardiac catheterization, rats in group SI were sham injured on the back by immersing in 37 ℃ warm water for 18 s, and rats in the other 3 groups were inflicted with 30% total body surface area (TBSA) full-thickness scald on the back by immersing in 97 ℃ hot water for 18 s. Rats in group SI were not treated after the injury, while rats in the other 3 groups were performed fluid resuscitation for 24 h through jugular vein catheter with micro syringe pump according to the Parkland formula. They were given 4.0 mL·kg^-1·% TBSA^-1 normal saline during the first 24 h, of which they were given half of the total amount for the first 8 h, and they were given half of the total amount for the second and third 8 h. Rats in group SR were infused normal saline only, while rats in group SD and group MD were infused normal saline+ 1.25 μg·kg^-1·min^-1dopamine and normal saline+ 6.00 μg·kg^-1·min^-1 dopamine respectively. Volume of 0.5 mL venous blood of all rats were taken through the cardiac catheter with serum separated at post injury hour (PIH) 1, 3, 6, 12, and 24. Serum content of cardiac troponin I (cTnI) was determined by enzyme-linked immunosorbent assay; serum content of diamine oxidase (DAO) was detected by ultraviolet spectrophotometer; serum content of β₂-microglobulin (β₂-MG) was determined by latex-enhanced immunoturbidimetric assay; serum content of total bile acid (TBA) was determined by enzyme colorimetry; serum content of lactic acid, malondialdehyde, and myeloperoxidase (MPO) was determined by ultraviolet spectrophotometer. Data were processed with analysis of variance for repeated measurement, one-way analysis of variance, least significant difference test, and Bonferroni correction. Results (1) At PIH 1, 3, 6, 12, and 24, serum content of cTnI of rats in group SR, group SD, and group MD [(2.69±0.19), (3.04±0.19), (4.96±0.25), (6.88±0.28), (4.75±0.31) μg/L, (2.70±0.14), (3.08±0.13), (5.06±0.19), (7.11±0.21), (4.89±0.16) μg/L, (2.18±0.14), (2.54±0.09), (3.97±0.14), (5.46±0.34), (3.32±0.33) μg/L] were higher than that in group SI [(1.70±0.08), (1.70±0.08), (1.69±0.11), (1.69±0.08), (1.70±0.08) μg/L, P<0.05], serum content of cTnI of rats in group SR and group SD was similar (P>0.05), and serum content of cTnI of rats in group MD was lower than that in group SR and group SD (P<0.05). (2) At PIH 1 to 24, serum content of DAO of rats in group SR, group SD, and group MD was higher than that in group SI (P<0.05), serum content of DAO of rats in group SR and group MD was similar (P>0.05), and serum content of DAO of rats in group SD was lower than that in group SR and group MD (P<0.05). (3) At PIH 1 to 24, serum content of β₂-MG of rats in group SR, group SD, and group MD was higher than that in group SI (P<0.05), serum content of β₂-MG of rats in group SR and group MD was similar (P>0.05), and serum content of β₂-MG of rats in group SD was lower than that in group SR and group MD (P<0.05). (4) At PIH 1 to 24, serum content of TBA of rats in group SR, group SD, and group MD was similar (P>0.05) and higher than that in group SI (P<0.05). (5) At PIH 1 to 24, serum content of lactic acid of rats in group SR, group SD, and group MD was higher than that in group SI (P<0.05), serum content of lactic acid of rats in group SR and group MD was similar (P>0.05), and serum content of lactic acid of rats in group SD was lower than that in group SR and group MD (P<0.05). (6) At PIH 1 to 24, serum content of malondialdehyde and MPO of rats in group SR, group SD, and group MD was higher than that in group SI (P<0.05), serum content of malondialdehyde and MPO of rats in group SR and group MD was similar (P>0.05), and serum content of malondialdehyde and MPO of rats in group SD was significantly lower than that in group SR and group MD (P<0.05). Conclusions With effective liquid recovery, dopamine of MD can improve early cardiac function of rats with severe scald, while dopamine of SD can alleviate tissue ischemia and hypoxia, reduce oxygen free radical damage in internal organs, and improve functions of intestine and kidney.