Response of cardiac endothelial cells to burn plasma and PMN exposure

We have shown that thermal injury impairs cardiac function and exposure of myocytes to bum plasma or PMNs diminishes cell viability, inhibits cGMP production, and induces creatinine kinase. Whether exposure of cardiac endothelial cells to bum plasma produces injury or dysfunction has not been studied. In this study, NZW rabbits were anesthetized (Ispflurane), given a 35% TBSA full thickness scald burn and resuscitated with a lactated Ringer's solution, (4cc/kg/TBSA for 24 hours), or were sham burned. All serum samples were obtained at 24 hrs and frozen at -70°. Neutrophils preps (isolated at 24 hrs postburn) yielded >95% PMN and >95% viability. Rabbit cardiac endothelial cells were isolated by coronary perfusion with Ca²-free-collagenase buffer. Endothelial cells were purified under selective growth conditions; a three day 10% CO₂ Incubation and several passages in L-vallne free media. Endothelial cells (2.5×10⁸/well) were examined under various experimental conditions: including treatment with Hanks buffer alone; buffer plus 10% sham plasma, buffer plus 10% burn plasma; buffer plus PMNs isolated from bum animals (2×10⁸/well). Supematants were assayed at 2 hours and 24 hours for creatinine kinase (CK). lactate dehydrogenase (LDH), nitrite production (NO₂) and cell viability. Incubation with bum plasma caused an increase of CK at 2 hours (98.5±2 U/ml. vs. 3.310.07) and 24 hours (84.9±1 vs. 2.5±0.02) over sham plasma treatments. Similarly, LDH was induced by burn plasma at 2 hours (130.6±34 vs. 39.2126) and 24 hours (94.7±30 vs. 55.4±26). Treatment with bum PMNs induced LDH at 2 hours and 24 hours (94.8±3 and 196.2±14), but minimally stimulated CK production (17.9±2.6 and 10.3±0.4). Endothelial cell viability and nitrite production were unaffected by experimental conditions. These data indicate bum plasma and PMNs can injure cardiac endothelial cells and this may contribute to cardiac dysfunction Induced by thermal trauma.