The effects of insulin deprivation and replacement on adipose tissue metabolism were investigated in vivo with microdialysis in nine insulin-dependent diabetic patients with no residual insulin secretion. Dialysis probes, implanted in abdominal subcutaneous fat, were continuously perfused, and tissue dialysate concentrations of glycerol (lipolysis index), glucose, lactate, and pyruvate were determined. Comparisons were made with respective metabolite levels in venous plasma. After termination of intravenous insulin infusion, free insulin in plasma fell from 130 to 70 pM. At the same time, glucose levels in plasma and adipose tissue rose in parallel. However, the relative increase in glucose levels was greater in adipose tissue than in blood. On the other hand, the increase in glycerol concentration in adipose tissue (35%) was markedly < that in venous plasma (250%). Lactate and pyruvate levels in adipose tissue and blood remained unchanged. After the resumption of intravenous insulin, free insulin in plasma rose to ∼600 pM. At the same time, the glucose levels in blood and adipose tissue decreased rapidly, and the glycerol concentration in these tissues decreased to 50% of the baseline levels. The lactate and pyruvate levels in subcutaneous tissue increased briefly after insulin replacement, whereas the lactate but not pyruvate levels in blood showed a similar increase. The α- or β-blocking agents phentolamine and propranolol in the ingoing tissue perfusate did not influence tissue glycerol at any time during the experiment. We concluded that insulin-induced changes in circulating metabolites only partly reflect variations in adipose tissue substrate kinetics. During insulin deprivation, glucose is accumulated in the adipose tissue extracellular compartment, probably because of reduced utilization by the adipocytes. The increase in lactate and pyruvate levels in adipose tissue after insulin replacement may be explained by local metabolite production. The lipolytic activity in abdominal subcutaneous adipose tissue is only modestly enhanced during relative insulin deficiency, which is in contrast to overall lipolytic activity. Finally, adrenergic mechanisms do not seem to be involved in the changes in the lipolysis rate, which are induced by hypoinsulinemia and hyperinsulinemia.
Original Articles|
June 01 1991
Effects of Insulin Deprivation and Replacement on In Vivo Subcutaneous Adipose Tissue Substrate Metabolism in Humans
Eva Hagström-Toft;
Eva Hagström-Toft
Department of Medicine and the Research Center, Huddinge Hospital
Huddinge
; and the Department of Pharmacology, Karolinska Institute
Stockholm, Sweden
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Peter Arner;
Peter Arner
Department of Medicine and the Research Center, Huddinge Hospital
Huddinge
; and the Department of Pharmacology, Karolinska Institute
Stockholm, Sweden
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Birgitta Näslund;
Birgitta Näslund
Department of Medicine and the Research Center, Huddinge Hospital
Huddinge
; and the Department of Pharmacology, Karolinska Institute
Stockholm, Sweden
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Urban Ungerstedt;
Urban Ungerstedt
Department of Medicine and the Research Center, Huddinge Hospital
Huddinge
; and the Department of Pharmacology, Karolinska Institute
Stockholm, Sweden
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Jan Bolinder
Jan Bolinder
Department of Medicine and the Research Center, Huddinge Hospital
Huddinge
; and the Department of Pharmacology, Karolinska Institute
Stockholm, Sweden
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Address correspondence and reprint requests to Jan Bolinder, MD, Associate Professor, Department of Medicine, M54, Huddinge Hospital, S-141 86 Huddinge, Sweden.
Diabetes 1991;40(6):666–672
Article history
Received:
March 26 1990
Revision Received:
January 18 1991
Accepted:
January 18 1991
PubMed:
2040382
Citation
Eva Hagström-Toft, Peter Arner, Birgitta Näslund, Urban Ungerstedt, Jan Bolinder; Effects of Insulin Deprivation and Replacement on In Vivo Subcutaneous Adipose Tissue Substrate Metabolism in Humans. Diabetes 1 June 1991; 40 (6): 666–672. https://doi.org/10.2337/diab.40.6.666
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