3.6.1.8 3-isobutyl-1-methylxanthine activation in preincubation 3.6.1.8 cAMP weak activation 3.6.1.8 glucose activation in preincubation 3.6.1.8 NaF 20 mM 3.6.1.8 NaN3 10 mM 3.6.1.8 oleic acid -