Pepe I M, Panfoli I, Cugnoli C
FEBS Lett. 1986 Jul 14;203(1):73-6. doi: 10.1016/0014-5793(86)81439-9.
Guanylate cyclase activity was measured in disrupted rod outer segments of the toad retina. The experiments showed that cGMP is synthesized from GTP at a rate of 3 +/- 1 nmol/min per mg protein. In darkness this value is largely independent of the Ca2+ concentration, while it is enhanced by flashes of light of increasing intensity upon lowering Ca from 10-5 to 10-8 M. In view of recent observations that shortly after a flash of light calcium activity inside the photoreceptor cell decreases, it seems likely that calcium plays a regulatory role in cGMP metabolism in visual excitation.
在蟾蜍视网膜的破碎视杆外段中测量了鸟苷酸环化酶的活性。实验表明，环磷酸鸟苷（cGMP）由鸟苷三磷酸（GTP）合成的速率为每毫克蛋白质3±1纳摩尔/分钟。在黑暗中，该值在很大程度上与钙离子（Ca2+）浓度无关，而当Ca2+浓度从10^-5降至10^-8摩尔时，强度不断增加的闪光会增强该值。鉴于最近的观察结果，即光闪后不久光感受器细胞内的钙活性会降低，钙似乎在视觉兴奋中的cGMP代谢中起调节作用。
