Document Detail


In the absence of counterregulatory hormones, the increase in hepatic glucose production during insulin-induced hypoglycemia in the dog is initiated in the liver rather than the brain.
MedLine Citation:
PMID:  8922369     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We have previously demonstrated that the liver can release glucose in response to insulin-induced hypoglycemia, despite the absence of glucagon, epinephrine, cortisol, and growth hormone. The aim of this study was to determine whether this is activated by liver or brain hypoglycemia. We assessed the response to insulin-induced hypoglycemia in the absence of counterregulatory hormones in overnight-fasted conscious adrenalectomized dogs that were given somatostatin and intraportal insulin (30 pmol x kg(-1) x min(-1)) for 360 min. Glucose was infused to maintain euglycemia for 3 h and then to allow limited peripheral hypoglycemia for the next 3 h. During peripheral hypoglycemia, five dogs received glucose via both carotid and vertebral arteries to maintain cerebral euglycemia (H-EU group) concurrently with peripheral hypoglycemia, while six dogs received saline in these vessels to allow simultaneous cerebral and peripheral hypoglycemia (H-HY group). Throughout the study, arterial insulin was 1,675 +/- 295 and 1,440 +/- 310 pmol/l in the H-HY and H-EU groups, respectively. Glucose fell from 6.2 +/- 0.3 to 2.1 +/- 0.0 mmol/l and from 5.8 +/- 0.3 to 1.9 +/- 0.1 mmol/l in the last hour in the H-HY and H-EU groups, respectively (P < 0.05 for both). Norepinephrine rose from 1.12 +/- 0.35 to 2.44 +/- 0.69 nmol/l and from 1.09 +/- 0.07 to 1.74 +/- 0.16 nmol/l in the last hour in the H-HY and H-EU groups, respectively (P < 0.05 for both; no difference between groups). Glucagon, epinephrine, and cortisol were below the limits of detection. The liver switched from uptake to output of glucose during peripheral hypoglycemia in both the H-HY (-7.1 +/- 2.1 to 5.4 +/- 3.1 micromol x kg(-1) x min(-1)) and H-EU (-7.9 +/- 3.5 to 3.4 +/- 1.7 micromol x kg(-1) x min(-1)) groups (P < 0.05 for both; no difference between groups). Alanine levels and net hepatic alanine uptake fell similarly in both groups. There were increases (P < 0.05) in glycerol (12 +/- 3 to 258 +/- 47 micromol/l) and nonesterified fatty acid (194 +/- 10 to 540 +/- 80 micromol/l) levels and in total ketone production (0.4 +/- 0.1 to 1.1 +/- 0.2 micromol x kg(-1) x min(-1)) in the H-HY group, but these parameters did not change in the H-EU group. These data clearly indicate that the lipolytic and hepatic responses to hypoglycemia are driven by differential sensing mechanisms. Thus, during insulin-induced hypoglycemia, when counterregulatory hormones are absent, liver hypoglycemia triggers the increase in hepatic glucose production, whereas cerebral hypoglycemia causes the increases in lipolysis and ketogenesis.
Authors:
C C Connolly; S R Myers; D W Neal; J R Hastings; A D Cherrington
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Diabetes     Volume:  45     ISSN:  0012-1797     ISO Abbreviation:  Diabetes     Publication Date:  1996 Dec 
Date Detail:
Created Date:  1996-12-30     Completed Date:  1996-12-30     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0372763     Medline TA:  Diabetes     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1805-13     Citation Subset:  AIM; IM    
Affiliation:
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
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MeSH Terms
Descriptor/Qualifier:
Adrenalectomy
Alanine / blood
Animals
Blood Glucose / metabolism
Brain / metabolism*
Dogs
Fatty Acids, Nonesterified / blood
Female
Glucose / biosynthesis*
Glycerol / blood
Hormones / pharmacology*
Hypoglycemia / chemically induced,  metabolism*
Insulin* / administration & dosage,  blood
Lactic Acid / blood
Liver / drug effects,  metabolism*
Male
Norepinephrine / blood
Portal Vein
Somatostatin / pharmacology
Grant Support
ID/Acronym/Agency:
2P60-DK-20593/DK/NIDDK NIH HHS; 2R01-DK-18243/DK/NIDDK NIH HHS
Chemical
Reg. No./Substance:
0/Blood Glucose; 0/Fatty Acids, Nonesterified; 0/Hormones; 11061-68-0/Insulin; 50-21-5/Lactic Acid; 50-99-7/Glucose; 51-41-2/Norepinephrine; 51110-01-1/Somatostatin; 56-41-7/Alanine; 56-81-5/Glycerol

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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