A concentration gradient of glucose from liver to plasma

Concentrations of glucose in plasma water and liver water were determined in rats under a number of conditions. In fasted and fed postadsorptive rats, the concentration of glucose in plasma water averaged 5.5 +/- 0.5 and 6.8 +/- 0.2 mmol/L, respectively. The concentration in liver water was 8.2 +/- 0.9 and 11.1 +/- 1.1 mmol/L, respectively (mean +/- SD). The concentration ratio of liver water to plasma water (LW/PW) was 1.52 +/- 0.1 (range, 1.4 to 1.7; n = 7) in fasted rats and 1.64 +/- 0.39 (range, 1.38 to 2.0; n = 10 [mean +/- SD]) in fed rats. Fasted rats treated with glucagon contained no liver glycogen. The concentration of glucose in plasma water was 7.1 +/- 0.3 mmol/L and in liver water 9.2 +/- 0.5 mmol/L, and the LW/PW averaged 1.35 +/- 0.08 (range, 1.23 to 1.45; n = 8). Insulin-injected hypoglycemic rats contained very little glycogen. The LW/PW was 2.7 +/- 0.2. In fasted rats infused intragastrically with 30 mg/min/kg glucose, the concentration of glucose in mixed portal-arterial plasma water entering the liver averaged 10.3 +/- 0.8 mmol/L and that in liver water 12.4 +/- 1.3 mmol/L (mean +/- SD), with the LW/PW averaging 1.21 +/- 0.1 (range, 1.08 to 1.4; n = 8). Fasted rats were infused with 3.4 mg/min/kg sodium lactate labeled with 14C and 13C and with a trace amount of [3-3H]glucose. The glucose concentration in arterial plasma water averaged 6.4 +/- 1.0 mmol/L and in liver water 14.6 +/- 4.4 mmol/L (mean +/- SD).(ABSTRACT TRUNCATED AT 250 WORDS)