Fig. 2. Free amino acid (AA) levels in blood plasma (% of 0 h samples; means ± s.e.m.) collected synchronically from the hepatic portal vein (HPV; black squares) and dorsal aorta (DA; white squares) in free-swimming rainbow trout after a single meal. The major AA uptake patterns are represented by the sum of taurine, glutamic acid, glutamine, glycine, alanine, lysine, arginine and serine (type I; A), the sum of valine, cysteine, methionine, isoleucine, leucine, tyrosine and phenylalanine (type II; B) and the sum of threonine and tryptophan (type III; C). ^*Statistically significant difference (^*P<0.05, ^**P<0.01, ^***P<0.001) between the DA and HPV values at a given sample time. Values from the same vessel followed by the same letter do not differ significantly (P>0.05).