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大鼠口服茶碱0.5～3小时后,脑中cAMP和cGMP都有改变。当茶碱剂量为25 mg/kg或稍高时可使cAMP和cGMP水平增加;当茶碱剂量减为10mg/kg时,cGMP的水平则明显下降。实验结果表明茶碱对大鼠脑中的环核苷酸水平的影响是由两种原因引起的:(1)茶碱对裂解cAMP和cGMP的磷酸二酯酶(PDE)有抑制作用;(2)茶碱同腺苷有竞争作用。 茶碱是裂解cAMP和cGMP的磷酸二酯酶的理想抑制剂,它对PDE的抑制作用在低米氏常数时较高米氏常数时为大。茶碱抑制裂解cAMP的PDE的作用较抑制裂解cGMP的PDE的作用强。
0.5 to 3 hours after oral administration of theophylline in rats, brain cAMP and cGMP have changed. When theophylline dose was 25 mg / kg or slightly higher cAMP and cGMP levels were increased; when theophylline dose was reduced to 10 mg / kg, cGMP levels were significantly decreased. The results show that the effects of theophylline on the cyclic nucleotide levels in the rat brain are caused by two reasons: (1) theophylline has an inhibitory effect on phosphodiesterase (PDE) that cleaves cAMP and cGMP; (2) Theophylline has a competitive effect with adenosine. Theophylline is an ideal inhibitor of phosphodiesterase that cleaves cAMP and cGMP, and its inhibitory effect on PDE is large at high Mie constants at low Mie constants. Theophylline inhibits the action of PDE that cleaves cAMP more strongly than PDE that cleaves cGMP.