@ ) Both nitric oxide synthase @ and soluble guanylate cyclase are expressed in higher levels in vascular tissues during sepsis ; @ ) both proteins physically interact and nitric oxide synthase @ blockade inhibits cyclic guanosine monophosphate production ; @ ) pharmacological blockade of nitric oxide synthase @ using @-nitroindazole or S-methyl-L-thiocitrulline reverts the hyporesponsiveness to phenylephrine and increases the vasoconstrictor effect of norepinephrine and phenylephrine .