ISSN:
1432-0428
Keywords:
Keywords Metformin
;
insulin receptor
;
glucose transport
;
glycogen synthase
;
glycogenesis
;
Xenopus laevis oocytes.
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Xenopus laevis oocytes were chosen as the in vitro model for this study with the aim of reconsidering metformin action on the main insulin-responsive glucose pathway. Metformin alone, when present at a therapeutic dose (20 μmol/l) in the incubation medium, did not alter the basal rate of glucose uptake or of glycogen synthesis as measured by [U-14C] D-glucose incorporation. The drug had no effect on the main rate-limiting enzyme implicated in this pathway, i. e. glycogen synthase. In contrast, when combined with 2 μmol/l insulin, metformin led to a specific rise of both free and stored glucose, by 42.4 and 102.3 % respectively. Moreoever, a short-term preincubation of mature oocytes with metformin, but in the absence of glucose, enhanced significantly the amount of synthase a when stimulated by 50 nmol/l insulin (basal 17.4 ± 5.7 %, metformin 21.3 ± 4.1 %, insulin 31.2 ± 4.6 %, metformin together with insulin 62.7 ± 4.2 %, p 〈 0.005, n = 5). Interestingly, the microinjection of this biguanide, at a final concentration of 20 nmol/l, allowed a similar biochemical response. These data clearly suggest that metformin could act primarily at postreceptor steps which are thought to be key sites in controlling the cellular glucose homeostasis. [Diabetologia (1998) 41: 2–8]
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s001250050859
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