Document Detail

Prolonged administration in vivo of alpha and beta adrenergic agonists decreases insulin binding to rat myocardial membranes in vitro by different mechanisms.
MedLine Citation:
PMID:  1675412     Owner:  NLM     Status:  MEDLINE    
Male Sprague Dawley rats were continuously treated in vivo for 6, 12 and 20 hours with a combination of an alpha- (beta-) adrenoreceptor agonist and a beta- (alpha-) adrenoreceptor antagonist in subcutaneously implanted depot tablets. Crude membranes prepared from myocardial cells exhibited a decreased maximum binding of [125I]-insulin after 20 hours irrespective of the treatment applied. Scatchard and non-linear regression analysis of the displacement curves assuming two non-cooperative binding sites revealed a downregulation of the high affinity receptors for about 85% and a concomitant 2.5-fold increased receptor affinity under beta-adrenergic influence. In contrast, alpha-adrenergic treatment did not affect the receptor number but decreased the high affinity by 70%. The low affinity binding sites were virtually unaffected by the different treatments. The phospholipid and cholesterol contents of the membranes were not significantly altered. The phospholipid/cholesterol ratios after 12 and 20 hours of alpha-adrenergic treatment, however, were decreased. We suggest that the decreased binding activity of insulin receptors on rat myocardial membranes after continuous in vivo treatment with alpha- and beta- adrenergic agonists is mediated by different mechanisms.
G Desoye; U Ertl-Stockinger; S Porta
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Life sciences     Volume:  48     ISSN:  0024-3205     ISO Abbreviation:  Life Sci.     Publication Date:  1991  
Date Detail:
Created Date:  1991-07-12     Completed Date:  1991-07-12     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0375521     Medline TA:  Life Sci     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  2249-58     Citation Subset:  IM    
Department of Obstetrics and Gynecology, University of Graz, Austria.
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MeSH Terms
Adrenergic alpha-Agonists / pharmacology*
Adrenergic beta-Agonists / pharmacology*
Blood Glucose / metabolism
Drug Administration Schedule
Drug Implants
Heart / drug effects
Myocardium / metabolism*
Rats, Inbred Strains
Receptor, Insulin / drug effects*
Reg. No./Substance:
0/Adrenergic alpha-Agonists; 0/Adrenergic beta-Agonists; 0/Blood Glucose; 0/Drug Implants; EC, Insulin

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