Cellular mechanisms of burn-related changes in contractility and its prevention by mesenteric lymph ligation

Major burn injury results in impairment of left ventricular (LV) contractile function. There is strong evidence to support the involvement of gut-derived factor(s) transported in mesenteric lymph in the development of burn-related contractile dysfunction; i.e., mesenteric lymph duct ligation (LDL) prevents burn-related contractile depression. However, the cellular mechanisms for altered myocardial contractility of postburn hearts are largely unknown, and the cellular basis for the salutary effects of LDL on cardiac function have not been investigated. We examined contractility, Ca2+ transients, and L-type Ca2+ currents (ICa) in LV myocytes isolated from four groups of rats: 1) sham burn, 2) sham burn with LDL (sham + LDL), 3) burn (≈40% of total body surface area burn), and 4) burn with LDL (burn + LDL). Myocytes isolated from hearts at 24 h postburn had a depressed contractility (≈20%) at baseline and blunted responsiveness to elevation of bath Ca2+. Myocyte contractility was comparable in sham + LDL and...