Steurer G, Schütz W
Experientia. 1984 Sep 15;40(9):970-1. doi: 10.1007/BF01946463.
The stimulatory effect of nitro-compounds on arterial and hepatic guanylate cyclase became significantly depressed at 0.2 microM and higher concentrations of free Ca2+. The basal enzyme activity proved to be Ca2+-independent.