The influence on the metabolic response to endotoxin of three days of total parenteral nutrition with lipids high in gammalinolenic acid (18:3 omega 6, GLA) compared to soy oil (SO) was examined in acute operatively stressed guinea pigs. GLA is the precursor of dihomogammalinolenic acid (DHLA), the substrate for synthesis of "1" series prostaglandins such as PGE1, which have previously been shown to be protective in endotoxin lung injury and traumatic shock. Guinea pigs fed an intravenous diet containing black currant seed oil (BCO) emulsion (20% GLA) or soy oil emulsion (0% GLA) for 2.5 days had their arterial pH, pCO2, pO2, and bicarbonate measured at baseline and hourly during a 7-hr infusion of endotoxin (lipopolysaccharide (LPS), 2mg/kg) or saline. Plasma lactate and fatty acid profile analyses were performed at the end of the LPS infusion. Increased levels of GLA and DHLA were present in the plasma phospholipid fraction of animals fed the black currant seed oil diet, while soy-fed animals had only trace amounts of GLA. In addition, the ratio of DHLA to arachidonate was higher in animals receiving the black currant seed oil total parenteral nutrition (TPN). After 2 hr of LPS infusion, all animals exhibited the typical shock response resulting in metabolic acidosis characterized by a significant (p less than 0.05) drop in pH from 7.34 +/- .02 (SO) and 7.39 +/- .02 (BCO) at baseline to 7.14 +/- .05 and 7.22 +/- .04 by 7 hr for SO and BCO groups, respectively. Plasma lactate values at the end of the infusion were significantly elevated compared to saline in both groups (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)