NOS1 and heart failure: It has been suggested that rearrangement in nNOS subcellular localization in the presence of heart failure may play an important role in the downstream effects of NO on cardiac function; if that were the case, the sarcolemmal localization of nNOS in failing hearts would be expected to result in a reduction in PLB phosphorylation, contributing to impaired relaxation and depressed contractility secondary to a reduction in Ca2+ influx via ICa.