Possible Role of Phosphatidylinositol Turnover in Insulin Release from Isolated Rat Pancreatic Islets

1984 ◽  
Vol 16 (09) ◽  
pp. 458-460 ◽  
Author(s):  
K. Tanigawa ◽  
H. Kuzuya ◽  
H. Imura
1984 ◽  
Vol 247 (6) ◽  
pp. E701-E708 ◽  
Author(s):  
W. Phang ◽  
L. Domboski ◽  
Y. Krausz ◽  
G. W. Sharp

The mechanism of synergism between glucose and adenosine 3',5'-cyclic monophosphate (cAMP) on insulin release has been studied. Synergism may result from 1) inhibition of Na+-Ca2+ exchange by glucose and 2) a cAMP-induced sensitization of the release machinery to Ca2+. To distinguish between these two possibilities, isolated rat pancreatic islets were perifused with agents that raise intracellular levels of cAMP [3-isobutyl-1-methylxanthine (IBMX) and forskolin] and others that increase intracellular concentrations of Ca2+ either by blocking Na2+-Ca2+ exchange (ouabain and choline-Ringer solution) or by causing increased Ca2+ influx (KCl, carbachol, and 10 mM Ca2+). The results indicate that both the combination of cAMP and increased Ca2+ influx or blocked Na2-Ca2+ exchange and increased Ca2+ influx potentiated insulin release. When the relative potentiating abilities of cAMP and blocked Na2+-Ca2+ exchange were compared by determining the individual effects of IBMX and 1 mM ouabain (a concentration that causes similar inhibition of 45C2+ efflux as 16.7 mM glucose) in the presence of carbachol, cAMP was only 1.4 times more potent as a potentiating agent than blocked Na+-Ca2+ exchange. The greatest potentiation of insulin release was observed when Na+-Ca2+ exchange was blocked in the presence of increased levels of intracellular cAMP.


Diabetes ◽  
1986 ◽  
Vol 35 (1) ◽  
pp. 58-60 ◽  
Author(s):  
A. Alwmark ◽  
M. W. Stavinoha ◽  
C. W. Cooper ◽  
G. H. Greeley ◽  
J. C. Thompson

FEBS Letters ◽  
1976 ◽  
Vol 68 (2) ◽  
pp. 225-227 ◽  
Author(s):  
P. Schauder ◽  
C. McIntosh ◽  
J. Arends ◽  
R. Arnold ◽  
H. Frerichs ◽  
...  

Metabolism ◽  
1978 ◽  
Vol 27 (9) ◽  
pp. 1211-1214 ◽  
Author(s):  
Peter Schauder ◽  
Christopher McIntosh ◽  
Uwe Panten ◽  
Jan Arends ◽  
Rudolph Arnold ◽  
...  

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