ABSTRACT
I. Introduction In the past, adipose tissue was thought of simply as a passive depot for the storage of excess calories. Now, studies have revealed that fat tissue is an active endocrine organ with high metabolic activity. Indeed, excess fat has been shown to synthesize and secrete biologically active molecules that mediate complex respiratory and cardiovascular processes. One such molecule is leptin. In this chapter, we review the link between leptin and cardiorespiratory effects in obstructive sleep apnea (OSA). We discuss the neuromodulators of appetite and metabolism, with particular emphasis on leptin, and review the concept of leptin resistance. We present data that support a stimulatory role for leptin in respiratory function and a protective role for leptin in the development of pathologic cardiac hypertrophy and congestive heart failure (CHF). Finally, we close this chapter with a discussion of how leptin is linked to OSA, obesity hypoventilation syndrome (OHS), and conditions of chronic hypoxia.
