Fig. 4

Analyzing cAMP levels in response to activation of Gs- or Gi/o protein-coupled receptors in dispersed islets. a The unspecific activation of adenylyl cyclases by 10 μM forskolin resulted in an almost 8-fold increase of cAMP. b Activation of the highly expressed GLP-1R by its agonist induced a significant increase in cAMP (> 6-fold). c Incubation with 1 μM forskolin increased intracellular cAMP concentration which can be reduced by 1 μM Sst-14 due to activation of Gi/o protein-coupled SstR. Given are the means ± SEM of four to five experiments each performed in triplicates. Statistical significance was tested with the two-tailed paired t test (*p ≤ 0.05; **p ≤ 0.01)