3. CELLULAR ASPECTS OF ACTIVE TRANSPORT
141
TABLE II
AMINO ACIDS ABSORBED FROM THE LUMEN OF THE INTESTINE
OF VARIOUS ANIMAL SPECIES
Concentration
Amino acids
(M)
Methods
Species
Reference
L-Histidine
ΙΟ"
3
In vitro
Rat
(22)
In vivo
Rat
(22)
L-Methionine
ΙΟ"
3
In vivo
Rat
(22)
L-Valine
ΙΟ"
3
In vivo
Rat
(22)
L-Leucine
ΙΟ"
3
In vivo
Rat
(22)
L-Histidine
2 Χ 10"
2
In vivo
Rat
(23)
L-Methionine
2 Χ 10"
2
In vivo
Rat
(23)
L-Tryptophan°
5 Χ ΙΟ"
3
In vitro
Hamster
(24)
L-Phenylalanine
5 Χ ΙΟ"
3
In vitro
Hamster
(24)
L-Tyrosine
5 Χ ΙΟ"
3
In vitro
Hamster
(24)
L-Tyrosine
3 Χ ΙΟ"
3
In vitro
Chick
(25)
L-Tyrosine
3 Χ ΙΟ"
3
In vitro
Rabbit
(25)
L-Tyrosine
3 Χ ΙΟ"
3
In vitro
Hamster
(25)
L-Tyrosine
3 Χ ΙΟ"
3
In vitro
Rat
(25)
L-Methionine
7 Χ ΙΟ"
4
In vivo
Chick
(26)
L-Histidine
7 Χ ΙΟ"
4
In vivo
Chick
(26)
L-Alanine
ΙΟ"
2
In vitro
Green frog
6
(27)
Glycine
ΙΟ"
2
In vitro
Green frog
(27)
L-Histidine
ΙΟ"
2
In vitro
Green frog
(27)
L- Alanine
—
In vivo
Cat
(28)
L-Histidine
—
In vivo
Dog
(21)
L-Alanine
—
In vivo
Dog
(21)
0 Not concentrated at 2 X 10~
2 M.
b Rana clamitans.
vascularized intestinal loop in vivo or the Thiry-Vella fistulas (21).
It has thus been possible to show that some amino acids are concentrated in the serosal fluid whereas others are not. Table II lists the amino
acids absorbed from the lumen of the intestine of various species.
As far as the D enantiomorph of those amino acids is concerned, all
the data available so far indicate that in certain specific cases they also
seem to be accumulated, but to a lesser extent. Generally speaking also,
if both forms are present, the D form inhibits the accumulation of the
L form (Table III).
In the dog, L-histidine and L-alanine are accumulated to a greater
extent than the D form. In the cat in vivo experiments show that the