whereas dbcamp was the most potent agent in stimulating secretion of hcg , the n6 -- and o2'-monobutyryl derivatives of camp and phosphodiesterase inhibitors ( theophylline , papaverine , 3-isobutyl-1-methylxanthine ) also increased the secretion of the hormone .
C0039771
theophylline
C0000096
3-isobutyl-1-methylxanthine