Hirata M, Kohse K P, Chang C H, Ikebe T, Murad F
Department of Medicine, Stanford University School of Medicine, Palo Alto, California.
J Biol Chem. 1990 Jan 25;265(3):1268-73.
In order to clarify the mechanism(s) by which cyclic GMP inhibits the generation of inositol phosphates in rat aorta segments and cultured bovine aortic smooth muscle cells, we studied phosphoinositide hydrolysis and GTPase activity in homogenates and membrane preparations of cultured bovine aortic smooth muscle cells. Pretreatment of homogenate preparations with cyclic GMP plus ATP did not inhibit [8-arginine, 3H] vasopressin (AVP) binding, but resulted in a total suppression of the AVP-induced GTPase activation. The pretreatment with cyclic GMP and ATP also inhibited the formation of inositol phosphates induced by AVP in the presence of low concentrations of guanosine 5'-(gamma-thio)triphosphate (GTP gamma S), or by high concentrations of GTP gamma S alone. However, the formation of inositol phosphates by high concentrations of Ca2+ alone was not blocked. These results suggest that the ability of cyclic GMP to inhibit phosphoinositide hydrolysis results from an inhibition of a guanine nucleotide regulatory protein activation, and the interaction between guanine nucleotide regulatory protein and phospholipase C. While the precise site of this inhibition is not presently known, the inhibition by cyclic GMP is dependent upon the addition of ATP and probably entails a phosphorylation event since adenylylimidodiphosphate can not substitute for the ATP requirement.
为了阐明环磷酸鸟苷（cGMP）抑制大鼠主动脉段和培养的牛主动脉平滑肌细胞中肌醇磷酸生成的机制，我们研究了培养的牛主动脉平滑肌细胞匀浆和膜制剂中的磷酸肌醇水解及鸟苷三磷酸酶（GTPase）活性。用cGMP加ATP预处理匀浆制剂并不抑制[8-精氨酸，3H]血管加压素（AVP）结合，但导致AVP诱导的GTPase激活完全受到抑制。用cGMP和ATP预处理还抑制了在低浓度鸟苷5'-（γ-硫代）三磷酸（GTPγS）存在下AVP诱导的肌醇磷酸形成，或单独用高浓度GTPγS诱导的肌醇磷酸形成。然而，单独高浓度Ca2+诱导的肌醇磷酸形成并未被阻断。这些结果表明，cGMP抑制磷酸肌醇水解的能力源于对鸟嘌呤核苷酸调节蛋白激活的抑制，以及鸟嘌呤核苷酸调节蛋白与磷脂酶C之间的相互作用。虽然目前尚不清楚这种抑制的确切位点，但cGMP的抑制作用依赖于ATP的添加，并且可能涉及磷酸化事件，因为腺苷酰亚胺二磷酸不能替代ATP的需求。
