 ANP activation of the ANP catalytic receptor will stimulate its intracellular guanylyl cyclase activity to convert GTP to cGMP.cGMP will then stimulate cGMP-dependent protein kinase (PKG), which will then induce smooth muscle relaxation.This is particularly important in the vasculature, where vascular smooth muscle will bind ANP released as a result of increasing right atrial pressure and will cause the walls of the vasculature to relax.