Elimination of substances from the brain parenchyma: efflux via perivascular pathways and via the blood–brain barrier

Table 4 Influx and net flux of amino acids in the indicated species

	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
Glutamine^a				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

Values are stated in nmol g⁻¹ min⁻¹. Influxes have been measured only in rats. The only available measurements of net fluxes in rats, shown in the italicized column, failed to reach statistical significance
* Data used by Pardridge [379] in his comparison of influxes and net fluxes
^aIn some columns the values are for glutamine + asparagine as the assay used detected both
^bRelease measured during nervous stimulation
¹Banos et al. [369]
²Hawkins et al. [583]
³Mans et al. [584]
⁴Ennis et al. [415]
⁵Smith and Stoll [43]
⁶Brosnan et al. [378]
⁷Betz and Gilboe [365]
⁸Abdul-Ghani et al. [394]
⁹Pell and Bergman [585]
¹⁰Felig et al. [586]
¹¹Lying-Tunell et al. [587]
¹²Eriksson et al. [588]
¹³Grill et al. [589]
¹⁴Strauss et al. [590]

ISSN: 2045-8118