Wallace M A, Claro E
University of Tennessee, Department of Biochemistry, Memphis 38163.
Neurosci Lett. 1990 Mar 2;110(1-2):155-61. doi: 10.1016/0304-3940(90)90804-i.
Dopamine inhibited phosphoinositide breakdown as stimulated by carbachol in rat brain cortical membranes. The IC50 value was 14 +/- 2 microM for dopamine's inhibition of phosphatidylinositol hydrolysis as stimulated by 1 mM carbachol. The inhibition was found at low (0.1 microM), but not high (greater than 0.3 microM), concentrations of the non-hydrolyzable guanine nucleotide analog, GTP gamma S. Pharmacological characterization of the response indicated that the dopamine effects were mediated by D1 receptors. The assay conditions precluded any involvement of cyclic-AMP as a mediator of the dopamine response, and thus, a novel role is proposed for dopamine in cortex working through D1 receptors to inhibit phosphoinositide degradation.
多巴胺抑制了卡巴胆碱刺激大鼠脑皮质膜中磷酸肌醇的分解。多巴胺对1 mM卡巴胆碱刺激的磷脂酰肌醇水解的抑制作用的IC50值为14±2 microM。在低浓度（0.1 microM）而非高浓度（大于0.3 microM）的不可水解鸟嘌呤核苷酸类似物GTPγS时发现了这种抑制作用。对该反应的药理学特征分析表明，多巴胺的作用是由D1受体介导的。测定条件排除了环磷酸腺苷作为多巴胺反应介质的任何参与，因此，提出了多巴胺在皮质中通过D1受体发挥作用以抑制磷酸肌醇降解的新作用。
