13CO(2) peak value of L-[1-(13)C]phenylalanine breath test reflects hepatopathy.
BACKGROUND
Using a rat model of hepatectomy, we investigated whether the severity of hepatopathy could be quantitatively measured from changes in expiratory (13)CO(2) levels after intravenous administration of L-[1-(13)C]methionine or L-[1-(13)C]phenylalanine.


METHODS
Under nembutal anesthesia, 30 mg/kg L-[1-(13)C]phenylalanine or 40 mg/kg L-[1-(13)C]methionine was administered to rats through the femoral vein, and expiratory (13)CO(2) levels were measured for 15 min. A 30, 70, or 90% hepatectomy was performed. In the control group, simple laparotomy was performed. Breath test was conducted 20 min after laparotomy. We examined the correlation of the total (13)CO(2) output over 15 min or peak (13)CO(2) level with liver weight/body weight (%).


RESULTS
In breath test graphs, L-[1-(13)C]methionine did not show any peak level during measurement. L-[1-(13)C]phenylalanine showed a specific peak level 6 +/- 1 min after administration. The correlation coefficient between total (13)CO(2) output over 15 min after L-[1-(13)C]methionine administration and liver weight/body weight was 0.922 (P < 0.001). The correlation coefficient between total (13)CO(2) output over 15 min after L-[1-(13)C]phenylalanine administration and liver weight/body weight was 0.883 (P < 0.001). The correlation coefficient between peak L-[1-(13)C]phenylalanine level and liver weight/body weight was highest, 0.927 (P < 0.001).


CONCLUSIONS
In a breath test with intravenously administered L-[1-(13)C]methionine or L-[1-(13)C]phenylalanine, hepatopathy could be quantitatively evaluated by measuring expiratory (13)CO(2) levels over 15 min. After administration of L-[1-(13)C]phenylalanine, hepatopathy could be quantitatively evaluated in a short period by measuring the peak expiratory (13)CO(2) level.
Ishii
Y
Y
Department of Pharmacology, 3rd Department of Surgery, Nihon University School of Medicine, Itabashi-ku, Tokyo, 173, Japan.
Asai
S
S
Kohno
T
T
Suzuki
S
S
Ishii
M
M
Hosoi
I
I
Fujii
M
M
Iwai
S
S
Ishikawa
K
K
D000818:Animals; D001835:Body Weight; D001944:Breath Tests; D002245:Carbon Dioxide; D002247:Carbon Isotopes; D006498:Hepatectomy / Q000379:methods; D008099:Liver / Q000473:pathology; D008107:Liver Diseases / Q000175:diagnosis*; D008297:Male; D009929:Organ Size; D010649:Phenylalanine; D051381:Rats; D017208:Rats, Wistar; D012119:Respiration
D002247:Carbon Isotopes; D002245:Carbon Dioxide; D010649:Phenylalanine