RT Journal Article
SR Electronic
T1 Activation of liver guanylate cyclase by paraquat: possible role of superoxide anion.
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 162
OP 164
VO 209
IS 1
A1 D L Vesely
A1 B Watson
A1 G S Levey
YR 1979
UL http://jpet.aspetjournals.org/content/209/1/162.abstract
AB Paraquat, a herbicide which is known to increase intracellular levels of superoxide anion (O2-), stimulated guanylate cyclase [GTP pyrophosphate-lyase (cyclizing), EC 4.6.1.2.] activity. This stimulation by paraquat was seen at concentrations as low as 0.005 mM. The activation of guanylate cyclase by paraquat was not blocked by KCN, an inhibitor of superoxide dismutase [EC 1.15.1.1.], suggesting that the activation process probably does not involve superoxide dismutase which converts superoxide anion to hydrogen peroxide and ultimately to hydroxyl radical. Catalase [EC 1.11.1.6.] did not block the paraquat activation of guanylate cyclase indicating that hydrogen peroxide was probably not involved in the activation process. Butylated hydroxytoluene, a hydroxyl radical scavenger, also had no effect on the paraquat activation of guanylate cyclase activity. Superoxide dismutase inhibited the paraquat activation of guanylate cyclase. Thus, it would appear that superoxide ion itself can activate guanylate cyclase circumventing any requirement for hydroxyl radical formation.