Right and left ventricular myocytes originate from different cellular progenitors; however, it is unknown whether these cells differ in their response to endotoxemia. We hypothesized that: 1) the percentage of endotoxemic functional depression within the right ventricle would be smaller than that of the left ventricle; and 2) that these better RV function would correlate to lower levels of right ventricular TNF productionresults would be due to a greater degree of TNF resistance within right ventricular tissue. Adult SD rats were divided into right and left control and endotoxin groups. Controls received vehicle, while endotoxin groups received 20mg/kg LPS i.p. Hearts were excised either 2h or 6h after injection. Hearts excised at 2h were assayed for TNF, IL-6, TNFR1, and TNFR2 F and IL-6 via ELISA, while hearts excised at 6h hours were assayed via Langendorff. The percentage of cardiac functional depression, exhibited as developed pressure, contractility, and rate of relaxation (expressed as percentage of control) was significantly smaller in right ventricles compared to left ventricles following endotoxin exposure. Tissue levels of TNF were significantly elevated in both right and left ventricles two hours after endotoxin exposure, and right ventricular endotoxin groups expressed higher levels of TNF compared to their left ventricular counterparts. No significant differences in IL-6, TNFR1, or TNFR2 levels were noted between endotoxin exposed ventricles seen. This is the first study to demonstrate that right and left ventricular function differs after endotoxin exposure.