The neonatal heart may be more vulnerable to stress in face of inadequate carnitine supply due to low carnitine tissue levels, high metabolic rate and dependence on fatty acid oxidation. To test the hypothesis that carnitine deprivation impairs myocardial performance, newborn piglets received parenteral nutrition that was either carnitine-free (CARN -, n= 6) or supplemented with 400 mg/l L-carnitine (CARN +, n= 5) for 2-3 weeks. Following administration of E.coli endotoxin in vivo (LPS 250μg/kg i.v.), left ventricular developed pressure (LVDP) and end diastolic pressure (EDP) were evaluated in the isolated perfused heart (aerobic, hypoxic and reoxygenated). Ventricular tissue was analyzed for ATP. Results: After LPS, blood pressure fell and was lower in CARN - than CARN + piglets(P<0.02). Atrial and pulmonary artery nitric oxide production was increased 3- to 7-fold over non-LPS controls. Mean LVDP and EDP (±SD) values are shown below. During reoxygenation, defibrillation was needed to convert 6/6 CARN -, but only 2/5 CARN + hearts. ATP concentrations tended to be lower in hearts from CARN - than CARN + piglets. The findings suggest that neonatal carnitine deprivation adversely affects performance of the LPS- and hypoxia-stressed heart. Table

Table 1
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(Funded by USPHS HD29273 and American Heart Association - LA Affiliate)