title: Discrepancy between biological activity of thymosin and its cyclic nucleotide-modulating activity.
abstract: We have studied cyclic adenosine 3':5'-monophosphate (cAMP) and cyclic 3':5'-guanosine monophosphate (cGMP) concentration in cord blood lymphocytes (CBL) and in adult peripheral blood lymphocytes (PBL) after stimulation with thymosin V-1 and V-2. At concentrations of 100 micrograms/ml, thymosin V-1 produced an 85% increase of cAMP in adult PBL, alterations being demonstrated within 1 min, whereas it did not affect the cAMP level in CBL which have a nine times higher basal level than PBL. On the other hand, thymosin V-1 did not have any effect on cGMP in CBL nor in adult PBL. Thymosin V-2 which inhibits E-rosette formation also increased cAMP in adult PBL like thymosin V-1. The increasing effect of thymosin V-1 on cAMP was observed even when cAMP phosphodiesterase was completely inhibited with isobutyl methylxanthine. From these data it was assumed that thymosin probably acts through the stimulation of adenylate cyclase.
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism; D000328:Adult; D000628:Aminophylline / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis; D005312:Fetal Blood / Q000166:cytology; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism; D009712:Nucleotides, Cyclic / Q000096:biosynthesis*; D012397:Rosette Formation; D013947:Thymosin / Q000494:pharmacology*; D013951:Thymus Hormones / Q000494:pharmacology*
chemical_list: D009712:Nucleotides, Cyclic; D013951:Thymus Hormones; D000628:Aminophylline; D013947:Thymosin; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D000262:Adenylyl Cyclases; D015056:1-Methyl-3-isobutylxanthine