Changes of myocardial mitochondrial Ca2+ transport and mechanism in the early stage after severe burns

Abstract

Objective: To investigate the change of myocardial mitochondrial Ca2+ transport and its mechanism in the early stage after burns. Methods: Forty-eight Wistar rats were randomized into a normal control group (n=8) and a burns group (n=40). The rats of the burns group were given a 30%TBSA full-thickness. Myocardial mitochondria were isolated from normal and scalded rats which were sacrificed at the 1st, 3rd, 6th, 12th and 24th hour post-burn. Mitochondrial Ca2+ transport velocity, membrane potential (MP), ATP content and cytosolic Ca2+ concentration [Ca2+]c were determined. The effects of exogenous ATP on mitochondrial Ca2+ transport velocity were also investigated. Results: Mitochondrial Ca2+ uptake velocity of the 1st hour post-burn was higher than that of the control, and Ca2+ release velocity did not change significantly, but mitochondrial Ca2+ transport velocity, MP and ATP content were all decreased at the 3rd, 6th, 12th and 24th hour post-burn. Mitochondrial Ca2+ uptake velocity was positively correlated with MP after burn, and Ca2+ release velocity with mitochondrial ATP content. [Ca2+]c was increased at the 3rd, 6th, 12th and 24th hour post-burn. Exogenous ATP increased myocardial mitochondrial Ca2+ uptake velocity of rats at the 3rd and 6th hour post-burn and Ca2+ release velocity at the 3rd, 6th and 12th hour post-burn. Conclusions: Increase of [Ca2+]c led to reinforcement of mitochondrial Ca2+ uptake at the beginning of the post-burns period. ATP depletion and MP collapse cause myocardial mitochondrial Ca2+ transport disorder in the following stages.