TPN-INDUCED SYMPATHETIC ACTIVATION IS RELATED TO DIET, BACTERIAL TRANSLOCATION, AND AN INTRAVENOUS LINE

Objective: To investigate the effects of an intravenous line and the a dministration of a total parenteral nutrition (TPN) formula by the par enteral and oral routes on bacterial translocation and urinary catecho lamine excretion in rodents. Methods: Rats were fed chow with or witho ut an intravenous line and a fat-free TPN solution either orally or in travenously for 5 consecutive days. Urine was collected on the first, third, and fifth days of feeding and quantitatively analyzed for norep inephrine and epinephrine excretion. Mesenteric lymph nodes were cultu red for bacteria at the end of the study (day 5). Results: Oral and in travenous TPN diets significantly increased norepinephrine excretion o ver time (P<.0001) compared with excretion in rats fed chow. Oral TPN diets increased epinephrine secretion after 5 days of feeding. The rou te of feeding TPN solution had no effect on norepinephrine or epinephr ine excretion. Chow-fed rats with intravenous lines tended to have inc reased norepinephrine excretion over 5 days of feeding compared with c how-Fed rats without intravenous lines (55% vs 13%, P=.08). Rats with bacterial translocation had greater norepinephrine excretion (mean +/- SEM, 136 +/- 23 pmol/mu mol of creatinine) than rats without bacteria l translocation (64 +/- 14 pmol/mu mol of creatinine) (P<.05). Conclus ions: Intravenous and oral fat-free, hypertonic glucose diets increase sympathetic nervous activity. This diet-induced sympathetic activity may be related to the presence of an intravenous line, bacterial trans location, the thermic effects of hypertonic glucose, and/or the absenc e of orally ingested food substances in rodent chow. In this model of rodent feeding, increased sympathetic activity may account for alterat ions in intestinal and immunologic defenses.