期刊
ENDOCRINE
卷 23, 期 1, 页码 11-16出版社
HUMANA PRESS INC
DOI: 10.1385/ENDO:23:1:11
关键词
islets; secretion; time-dependent suppression; second messengers; phospholipase C; desensitization
资金
- PHS HHS [41230] Funding Source: Medline
Glucose-induced insulin secretion is inhibited by 5-hydroxytryptamine (5HT). In the present studies the specificity of 5HT inhibition of release and the potential biochemical mechanisms involved were investigated. Dose-dependent inhibition of 15 mM glucose-induced secretion was induced by a prior 3 h incubation with 5HT. At the highest 5HT concentration (500 muM) employed, both first and second phase responses to 15 mM glucose were reduced 50-60%. In addition, this level (500 muM) of 5HT virtually abolished 10 mM glucose-induced secretion. In contrast, secretion in response to the protein kinase C activator phorbol 12-myristate 13-acetate (500 nM) was immune to 500 muM 5HT pretreatment. Glucose usage rates were comparable in both control and 500 muM 5HT-pretreated islets. However, the generation of inositol phosphates and the efflux of 3 H-inositol from H-3-inositol-prelabeled islets in response to stimulatory glucose were impaired in parallel with insulin secretion. Based on these observations the following conclusions were reached: (1) 5HT impairs glucose-induced insulin release by altering glucose-induced activation of phospholipase C. (2) Biochemical events distal to phospholipase C remain intact despite this proximal biochemical lesion. (3) Amperometric analysis of 5HT release from 5HT-pretreated islets must take into consideration its profound adverse impact on glucose-induced insulin secretion.
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