Limitation in glucose penetration from the liver into blood and other metabolic symptoms of ethanol withdrawal in rats

Opposing effects of chronic alcohol consumption on hepatic gluconeogenesis for female versus male rats

BACKGROUND

The impact of chronic alcohol consumption on hepatic gluconeogenesis (HGN) between males and females is unknown. To determine the effects of chronic alcohol consumption (8 weeks) on HGN, the isolated liver perfusion technique was used on 24-hr-fasted male and female Wistar rats.

METHODS

After surgical isolation, livers were perfused (single pass) for 30 min with Krebs-Henseleit bicarbonate buffer and fresh bovine erythrocytes with no added substrate (washout period). After the washout period, livers were perfused with lactate (10 mM) and [U-14C]lactate (15,000 dpm/ml) using the recirculation method.

RESULTS

There was no significant difference in HGN between males and females fed the control diet. In contrast, the females chronically fed the ethanol diet (FE) had significantly lower HGN rates (2.73 +/- 0.37 micromol/min x g liver protein(-1)), whereas males fed the ethanol diet (ME) had significantly higher HGN rates (4.99 +/- 0.45 micromol/min x g liver protein(-1)) than controls (3.83 +/- 0.34 micromol/min x g liver protein(-1)). Concomitant decreases were also observed for both 14C-lactate incorporation into 14C-glucose and rates of lactate uptake for FE, while corresponding increases were observed for 14C-lactate incorporation into 14C-glucose for ME. The livers from ME were able to convert a greater percentage of the lactate into glucose, resulting in the elevation in gluconeogenic capacity.

CONCLUSION

Chronic alcohol consumption lowers the hepatic gluconeogenic capacity from lactate in females and elevates HGN in males.

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)

Blood glucose and liver glycogen in the rat. Effects of chronic ethanol consumption and its withdrawal on the diurnal rhythms

In rats, chronic ethanol consumption results in moderate hypoglycemia with no great changes in the diurnal patterns of blood glucose and hepatic glucose. Marked alterations of the diurnal rhythm of liver glycogen were observed in ethanol-fed animals, the phase of the rhythm being shifted and the daily mean and minimum levels being lowered. After withdrawal of ethanol consumption, blood glucose remained at a nearly constant level for 18 h, but then decreased sharply causing the liver/blood gradient of glucose to increase up to 4. Liver glycogen varied with a small amplitude and a nearly inverted phase in withdrawn rats as compared to controls.