Rat1 Rat2 Rat3 Rat4 Rat5 Rat6 Dog7 Dog7 Cat8 Sheep9 Human10 Human11 Human12 Human13 Human14 Influx* Influx Influx Influx Influx Net Net* Net* Net Net Net Net Net Net Net Phenylalanine 6.5 7 8 13.2 − 0.6 0.12 0.01 2.2 0.06 0.3 − 0.5 Leucine 6.2 15 14.5 9.7 1.56 1.28 1.9 6 5.2 3.2 2.2 0.6 Isoleucine 1.8 4 5.7 0.78 0.46 1.5 3.1 1.2 1.4 0.7 0.3 Valine 1.3 1.8 2.9 1.26 0.37 2.7 11.0 1.7 0.8 − 1.7 Tyrosine 5.3 7 4.1 − 1.1 0 0.06 1.6 0.1 − 0.1 − 0.1 Methionine 1.6 1.7 − 1.1 0 − 0.12 1.0 0.6 0.2 0.2 Tryptophan − 1.1 Histidine 2.5 2.5 − 1.7 − 0.23 − 0.7 0.7 − 0.3 − 1.3 threonine 1.2 0.8 − 3.4 0.62 − 0.1 5.0 2.6 0.1 Arginine 1 − 7.4 − 0.2 − 0.05 2 0.7 − 0.5 − 0.1 Lysine 6.2 9 − 1.1 0.58 − 1.6 2.5 − 0.3 − 0.9 Glutamate 1.7 − 0.24 − 0.18 − 0.05 1.4 − 0.5 − 6 Glutaminea 11.6 1 − 15.4 − 6.6 − 4.3 − 1.94 − 7.4 11.0 − 20 − 20.4 nerv. stim.b glutamate − 1.26 nerv. stim.b glutamine − 6.69