l-[1-(13)C]Alanine is a useful substance for the evaluation of liver function

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]alanine.

Under nembutal anesthesia, 20 mg/kg l-[1-(13)C]alanine was administered to rats via the femoral vein, and expiratory (13)CO(2) levels were measured for 15 min. Then, 30, 70, or 90% hepatectomy was performed. In the control group, simple laparotomy was performed. A breath test was conducted 20 min after laparotomy. We examined the correlation of total (13)CO(2) output (S) or single point (13)CO(2) level (SP) every 1 min for 15 min with liver weight/body weight (LW/BW) (%).

In the control group, the breath test graph showed a specific peak level about 3 min after administration, but in all groups undergoing hepatectomy, it did not show any peak level during measurement. The correlation coefficient between S(12--15) after l-[1-(13)C]alanine administration and LW/BW was 0.902 (P < 0.0001). The correlation coefficient between SP(7) after l-[1-(13)C]alanine administration and LW/BW was highest, 0.908 (P < 0.0001). The severity of hepatopathy could also be evaluated, with significant differences in S(12-14) compared to control when the volume of resected liver was 30% or greater, but there was no significant difference between the groups undergoing 70 and 90% hepatectomy. However, the severity of hepatopathy could be evaluated, with significant differences in S(15) and SP(7) in all comparisons between groups.

In the breath test with intravenously administered l-[1-(13)C]alanine, the severity of hepatopathy could be quantitatively evaluated in a short period by measuring S(15) and SP(7).