Calculation of maximal removal rate of indocyanine green to measure hepatic functional mass in dogs by use of the nine-hour method.
OBJECTIVE
To establish a versatile and reliable procedure for the determination of indocyanine green maximal removal rate (ICG Rmax) to measure hepatic functional mass in dogs within 9 hours (9-hour method).


METHODS
Relation between 9-hour and standard 3-day methods was examined.


METHODS
101 healthy dogs.


METHODS
On investigation of the optimal technical conditions allowing completion of all procedures in a day, the appropriate IV administered doses of ICG were 0.125, 0.5, and 2.0 mg/kg of body weight, and the best blood sample collection times for obtaining plasma half-life at these 3 doses were before and 3, 6, and 9 minutes after ICG administration.


RESULTS
Comparison of the 9-hour with 3-day method yielded a correlation coefficient (r) of 0.84, indicating close (P < 0.01) correlation. In the 9-hour method, mean +/- SD of ICG Rmax in healthy dogs was 0.24 +/- 0.09 mg/kg/min in male (n = 62) and was 0.23 +/- 0.06 mg/kg/min in female (n = 21) Beagles, and was 0.21 +/- 0.10 mg/kg/min in male (n = 11) and 0.20 +/- 0.07 mg/kg/min in female (n = 7) mixed-breed dogs. In Beagles treated orally with carbon tetrachloride (0.1 ml/kg in gelatine capsules) thrice weekly during a 10-week period, plasma alanine transaminase activity plateaued at a high value (> 2,000 IU/L) on day 5, and remained at this value until the end of the study. The ICG Rmax changed accordingly: day 5, 0.17; day 10, 0.11; day 40, 0.05; and day 60, 0.06 mg/kg/min.


CONCLUSIONS
The 9-hour method for determination of ICG Rmax correlates favorably with the 3-day method.


CONCLUSIONS
This procedure may be practically applied in veterinary clinics in terms of prediction of hepatic functional mass, and for diagnosis of hepatotoxicosis induced by certain compounds.
Furuhama
K
K
Tokyo R & D Center, Daiichi Pharmaceutical Co Ltd, Japan.
Goi
S
S
Kawarabayashi
K
K
Maru
C
C
Inage
F
F
D000410:Alanine Transaminase / Q000097:blood; D000469:Alkaline Phosphatase / Q000097:blood; D000818:Animals; D001663:Bilirubin / Q000097:blood; D002251:Carbon Tetrachloride / Q000494:pharmacology; D004396:Coloring Agents / Q000493:pharmacokinetics*; D004285:Dogs / Q000097:blood / Q000502:physiology*; D005260:Female; D006207:Half-Life; D007208:Indocyanine Green / Q000493:pharmacokinetics*; D008099:Liver / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology*; D008111:Liver Function Tests; D008297:Male; D013997:Time Factors
D004396:Coloring Agents; D002251:Carbon Tetrachloride; D000410:Alanine Transaminase; D000469:Alkaline Phosphatase; D007208:Indocyanine Green; D001663:Bilirubin