Miroshnichenko V P, Busygina O G, Severina I S
Vopr Med Khim. 1989 Jul-Aug;35(4):60-6.
Activity of guanylate cyclase in rat thrombocytes exceeded the enzymatic activity in heart tissue 3.2- and 6.6-fold, if Mn2+ and Mg2+ were used as cofactors, respectively. Dithiothreitol (DTT) at concentrations 2 x 10(-5) M-2 x 10(-2) M activated guanylate cyclase both in rat heart and thrombocytes, while 2 x 10(-3) M of DTT exhibited the maximal stimulating effect: 3-fold in heart tissue and 4.5-fold in thrombocytes. Only slight 2-fold activation of guanylate cyclase was observed in myocardium in presence of 1 x 10(-4) M nitroprusside, whereas this effect was distinctly augmented up to 26-fold after preincubation of the enzyme with 1 x 10(-4) M of nitroprusside within 45 min at 4 degrees in presence of 2 x 10(-4) M DTT. The stimulating effect of nitroprusside was increased up to 52-fold after addition of 3 micrograms hemoglobin into the sample. Nitroprusside did not show any stimulating effect on the guanylate cyclase activity in rat thrombocytes under experimental conditions used. Possible causes of the phenomenon observed are discussed.
如果分别使用Mn2+和Mg2+作为辅助因子，大鼠血小板中鸟苷酸环化酶的活性比心脏组织中的酶活性高出3.2倍和6.6倍。浓度为2×10(-5)M - 2×10(-2)M的二硫苏糖醇（DTT）可激活大鼠心脏和血小板中的鸟苷酸环化酶，而2×10(-3)M的DTT表现出最大刺激作用：在心脏组织中为3倍，在血小板中为4.5倍。在存在1×10(-4)M硝普钠的情况下，心肌中仅观察到鸟苷酸环化酶有轻微的2倍激活，而在4℃下于2×10(-4)M DTT存在下将酶与1×10(-4)M硝普钠预孵育45分钟后，这种作用明显增强至26倍。在样品中加入3微克血红蛋白后，硝普钠的刺激作用增加到52倍。在所使用的实验条件下，硝普钠对大鼠血小板中的鸟苷酸环化酶活性未显示出任何刺激作用。讨论了观察到该现象的可能原因。
