Interrelationship between splanchnic and leg exchange of glucose and other blood‐borne energy metabolites during abdominal surgical trauma
ABSTRACT In eight patients undergoing cholecystectomy, measurements of leg blood flow, splanchnic blood flow and arterio-venous differences in oxygen, glucose, lactate, pyruvate, glycerol, 3-hydroxybutyrate and alanine were made. Splanchnic glucose release averaged 1 1 mmol/min. The uptake of glucose into leg tissue was low. The rise in arterial glucose concentration was about I mmol/h during surgery. At the end of surgery splanchnic oxygen uptake was increased by 70% and the alanine uptake into the same region was comparable to that described in patients with septic complications of surgery. The plasma insulin concentration was low compared with the arterial glucose level.The data suggest that during abdominal surgery (a) increase in arterial glucose concentration can be fully accounted for by slightly increased splanchnic glucose release and a low peripheral utilization; (b) release of gluconeogenic substrates from peripheral tissues is balanced by splanchnic uptake; (c) disturbed relation between glucose and insulin, enhanced gluconeogenesis, increased splanchnic oxygen uptake and fat-mobilizing lipolysis are in accordance with a raised sympatho-adrenergic activity.
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ABSTRACT: Arterial concentrations and net substrate exchange across the leg and splanchnic vascular bed were determined for glucose, lactate, pyruvate, and glycerol in healthy postabsorptive subjects at rest and during 40 min of exercise on a bicycle ergometer at work intensities of 400, 800, and 1200 kg-m/min. Rising arterial glucose levels and small decreases in plasma insulin concentrations were found during heavy exercise. Significant arterial-femoral venous differences for glucose were demonstrated both at rest and during exercise, their magnitude increasing with work intensity as well as duration of the exercise performed. Estimated glucose uptake by the leg increased 7-fold after 40 min of light exercise and 10- to 20-fold at moderate to heavy exercise. Blood glucose uptake could at this time account for 28-37% of total substrate oxidation by leg muscle and 75-89% of the estimated carbohydrate oxidation. Splanchnic glucose production increased progressively during exercise reaching levels 3 to 5-fold above resting values at the heavy work loads. Close agreement was observed between estimates of total glucose turnover during exercise based on leg glucose uptake and splanchnic glucose production. Hepatic gluconeogenesis-estimated from splanchnic removal of lactate, pyruvate, glycerol, and glycogenic amino acids-could supply a maximum of 25% of the resting hepatic glucose production but could account for only 6-11% of splanchnic glucose production after 40 min of moderate to heavy exercise. IT IS CONCLUDED THAT: (a) blood glucose becomes an increasingly important substrate for muscle oxidation during prolonged exercise of this type: (b) peripheral glucose utilization increases in exercise despite a reduction in circulating insulin levels: (c) increased hepatic output of glucose, primarily by means of augmented glycogenolysis, contributes to blood glucose homeostasis in exercise and provides an important source of substrate for exercising muscle.Journal of Clinical Investigation 01/1972; 50(12):2715-25. · 12.81 Impact Factor
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ABSTRACT: Splanchnic exchange of glucose, 20 individual amino acids, lactate, and pyruvate was studied in normal subjects in the postabsorptive state and after stimulation of endogenous insulin secretion by infusion of glucose at two dose levels. In the basal state, mean splanchnic glucose production was 3.4 mg/kg per min. A net uptake of lactate, pyruvate, and nine amino acids was observed, with alanine accounting for half of the total splanchnic-amino acid extraction. Infusion of glucose at 25 mg/kg per min for 20 min resulted in a fivefold increase in arterial insulin levels and in reversal of splanchnic glucose balance to a net uptake. Splanchnic uptake of alanine, glycine, phenylalanine, lactate, and pyruvate fell by 30-60% due to a reduction in fractional extraction of these substrates, inasmuch as their arterial concentrations did not decline.Administration of glucose at 2 mg/kg per min for 45 min resulted in a 19 mg/100 ml increase in arterial glucose concentration and a doubling of arterial insulin levels. Despite the small increment in insulin, hepatic glucose production fell by 85%. Splanchnic exchange of amino acids, lactate, and pyruvate was unaltered. Estimated total glucose utilization during the infusion was no greater than in the basal state, indicating lack of stimulation of peripheral glucose uptake. IT IS CONCLUDED THAT: (a) inhibition of hepatic glucose production associated with glucose infusion and large increments in insulin levels occurs in the absence of a decrease in the concentration of circulating gluconeogenic substrate, suggesting an hepatic rather than peripheral effect; (b) the liver is the primary target organ whereby glucose homeostasis is achieved with small increments in insulin; (c) the relatively greater sensitivity of the liver's response to insulin as compared with an effect of insulin on the peripheral tissues, may be a consequence of the higher levels of endogenous insulin in portal as compared with peripheral blood.Journal of Clinical Investigation 09/1971; 50(8):1702-11. · 12.81 Impact Factor
- American Heart Journal - AMER HEART J. 01/1940; 19(5):541-553.