Amplification of the effects of exosomes on left ventricular contractility upon previous exposure to lipopolysaccharide (LPS). Effect of exosomes on percentage of maximal positive (a) and negative (b) derivatives of left ventricular pressure in endotoxemic hearts. Data are mean ± standard error of the mean of experiments with exosomes from septic patients on normal hearts (septic ex, n = 9), exosomes from healthy individuals on normal hearts (healthy ex, n = 5), and exosomes from septic patients in endotoxemic hearts (septic ex + LPS, n = 4). *p < 0.05 versus baseline; #p < 0.05 versus septic ex; §p < 0.05 versus healthy ex (analysis of variance two-way, Tukey test). +dP/dtmax, maximal positive derivative of left ventricular pressure; -dP/dtmax, maximal negative derivative of left ventricular pressure.