Steen V M, Tysnes O B, Holmsen H
Department of Biochemistry, University of Bergen, Norway.
Biochem J. 1988 Jul 15;253(2):581-6. doi: 10.1042/bj2530581.
We have studied synergism between adrenaline (epinephrine) and low concentrations of thrombin in gel-filtered human platelets prelabelled with [32P]Pi. Suspensions of platelets, which did not contain added fibrinogen, were incubated at 37 degrees C to measure changes in the levels of 32P-labelled phosphatidylinositol 4,5-bisphosphate (PIP2), phosphatidylinositol 4-phosphate (PIP) and phosphatidate (PA), aggregation and dense-granule secretion after stimulation. Adrenaline alone (3.5-4.0 microM) did not cause a change in any parameter (phosphoinositide metabolism, aggregation and dense-granule secretion), but markedly enhanced the thrombin-induced responses over a narrow range of thrombin concentrations (0.03-0.08 units/ml). The thrombin-induced hydrolysis of inositol phospholipids by phospholipase C, which was measured as the formation of [32P]PA, was potentiated by adrenaline, as was the increase in the levels of [32P]PIP2 and [32P]PIP. The presence of adrenaline caused a shift to the left for the thrombin-induced changes in the phosphoinositide metabolism, without affecting the maximal levels of 32P-labelled compounds obtained. A similar shift by adrenaline in the dose-response relationship was previously demonstrated for thrombin-induced aggregation and dense-granule secretion. Also, the narrow range of concentrations of thrombin over which adrenaline potentiates thrombin-induced platelet responses is the same for changes in phosphoinositide metabolism and physiological responses (aggregation and dense-granule secretion). Our observations clearly indicate that adrenaline directly or indirectly influences thrombin-induced changes in phosphoinositide metabolism.
我们研究了肾上腺素（epinephrine）与低浓度凝血酶在预先用[32P]Pi标记的凝胶过滤人血小板中的协同作用。在不含添加纤维蛋白原的血小板悬液中，于37℃孵育，以测量刺激后32P标记的磷脂酰肌醇4,5-二磷酸（PIP2）、磷脂酰肌醇4-磷酸（PIP）和磷脂酸（PA）水平的变化、聚集和致密颗粒分泌情况。单独的肾上腺素（3.5 - 4.0 microM）不会引起任何参数（磷酸肌醇代谢、聚集和致密颗粒分泌）的变化，但在狭窄的凝血酶浓度范围（0.03 - 0.08单位/ml）内显著增强了凝血酶诱导的反应。肾上腺素增强了凝血酶通过磷脂酶C诱导的肌醇磷脂水解，这通过[32P]PA的形成来测量，[32P]PIP2和[32P]PIP水平的增加也如此。肾上腺素的存在使凝血酶诱导的磷酸肌醇代谢变化向左移动，而不影响获得的32P标记化合物的最大水平。肾上腺素在剂量 - 反应关系中的类似移动先前已在凝血酶诱导的聚集和致密颗粒分泌中得到证明。此外，肾上腺素增强凝血酶诱导的血小板反应的凝血酶浓度狭窄范围对于磷酸肌醇代谢变化和生理反应（聚集和致密颗粒分泌）是相同的。我们的观察清楚地表明，肾上腺素直接或间接影响凝血酶诱导的磷酸肌醇代谢变化。
