OBJECTIVETo study the effects of antisense p38α mitogen-activated protein kinase (hereinafter referred to as p38α) on myocardial cells exposed to hypoxia and burn serum.

METHODSThirty adult SD rats were inflicted with 40% TBSA full-thickness burn on the back to obtain burn serum. The myocardial cells were isolated from 80 neonatal SD rats and cultured, then they were divided into 4 groups according to the random number table: normal control group (N, ordinary culture without any treatment), hypoxia+burn serum group (HB, exposed to hypoxia after being treated with 10% burn rat serum), hypoxia+burn serum+infection group (HBI, exposed to hypoxia and 10% burn rat serum after being infected with antisense p38α gene-carrying adenovirus), hypoxia+burn serum+empty vector infection group (exposed to hypoxia and 10% burn rat serum after being infected with adenovirus empty vector). At post hypoxia hour (PHH) 1, 3, 6, and 12, mRNA and protein expression levels of p38α in the latter 3 groups were determined by RT-PCR and Western blotting, cell viability was determined by methylthianolyldiphenyl-tetrazolium bromide assay, and lactate dehydrogenase (LDH) activity was assayed at the same time point. At PHH 1, 6, and 12, apoptosis rate of myocardial cells was assessed by annexin V staining method. The indexes of group N were determined with the methods mentioned-above. Three wells were set at each time point in each group. Data were processed with one-way analysis of variance and LSD- t test.

RESULTS(1) At PHH 1, 3, and 6, the p38α mRNA level was higher in group HB than in group N and group HBI (with t values from 2.725 to 4.375, P values all below 0.05). (2) At PHH 1, 3, and 6, the p38α protein level was higher in group HB than those in group N and group HBI (with t values from 5.351 to 7.981, P values all below 0.01). (3) At PHH 3, 6, and 12, the cell viability in group HB (0.115 ± 0.007, 0.104 ± 0.006, 0.094 ± 0.005) was lower than that in group N (0.141 ± 0.014) and group HBI (0.136 ± 0.009, 0.124 ± 0.010, 0.112 ± 0.007, with t values from 2.357 to 6.812, P values all below 0.05). (4) The LDH activity was up-regulated in group HB as compared with that in group N and group HBI at each time point (with t values from 22.753 to 201.273, P values all below 0.01). (5) At PHH 1, 6, and 12, the apoptosis rate of myocardial cells in group HB [(5.4 ± 0.7)%, (8.7 ± 1.1)%, (13.6 ± 1.7)%] was higher than that of group N [(3.1 ± 0.3)%] and group HBI [(4.3 ± 0.5)%, (5.1 ± 0.7)%, (7.2 ± 0.9)%, with t values from 2.345 to 9.700, P < 0.05 or P < 0.01].

CONCLUSIONSAntisense p38α can protect the myocardial cells from the injury of hypoxia and burn serum.