Nitric Oxide and the Heart

Nitric oxide (NO) is traditionally known as a molecule released from the vascular endothelium that plays an important role in regulating vascular tone (1). However, in the heart, NO released from the vascular endothelium is involved in a number of important paracrine functions independent of vascular tone, as shown in Fig. 1. This chapter discusses the influence of NO on myocardial blood flow, substrate utilization, and oxygen consumption. The degree to which NO influences the contractility of the heart will also be discussed. NO has also been implicated in the control of apoptosis (2),which may have important clinical implications (3) in terms of the pathogenesis of heart failure (HF). As will be demonstrated in this chapter, NO has many more roles in the heart than simply dilating blood vessels.