ca2+ alone induced the atp-dependent secretion of [ 14c ] serotonin ( 50 % at a pca of 5.1 ) but the sensitivity of secretion to ca2+ was greatly enhanced by guanine nucleotides [ 6-fold by 100 microm gtp , 100-fold by 100 microm guanyl-5'-yl imidodiphosphate and greater than 500-fold by 100 microm guanosine 5'-o- ( 3-thiotriphosphate ) ] or by stimulatory agonists ( 10-fold by 2 units thrombin/ml and 4-fold by 1 microm 1-o-octadecyl-2-o-acetyl-sn-glyceryl-3-phosphorylcholine ) .
C0018353
gtp
C0079469
guanosine