these enzymes were also increased ( 1.5- to 2.0-fold ) by phosphodiesterase inhibitors ( caffeine , theophylline , theobromine , 3-isobutyl-1-methylxanthine , papaverine , mj 1988 , ro 20-1724 , or sq 20009 ) and the camp derivatives : 8-bromo-camp or dibutyryl camp .
C0039771
theophylline
C0000096
3-isobutyl-1-methylxanthine