HP18THE GOOD,THE FAT AND THE UGLY: METABOLIC HORMONES AND THE HEART

Obesity related cardiovascular disease has assumed epidemic proportions and it is important that we properly understand how hormones of metabolism influence cardiac function. Over the last 15 years a multitude of factors have been discovered that appear to play significant roles in energy balance and metabolism, markedly changing our view of fat and GI cells and their dynamic control and regulation of metabolism. This presentation will focus on how three recently discovered hormones Ghrelin, Leptin and Resistin may directly influence cardiac function. Ghrelin is predominately produced and secreted from the X/A cells of the stomach and studies suggest it can act as a cardioprotective agent. However, Ghrelin also acts to constrict the coronary arteries, which places potential limitations upon its therapeutic use. Leptin is produced by adipose tissue in proportion to fat deposition and appears to drive satiety signals in the body. In contrast, Leptin appears to antagonise cardiac function and it may drive the development of hypertension by impairing renal pressure natriuresis and down regulating endothelium derived vasorelaxant factors. The third factor, Resistin, was originally described from rat adipose tissue and was shown to impair insulin action and glucose control. In humans however, Resistin is primarily produced in inflammatory cells such as monocytes and macrophages. Resistin worsens the recovery of the heart from a period of experimental ischemia and promotes the release of inflammatory agents such as tumour necrosis factor‐alpha. Such actions may be partially responsible for the observed insulin resistance after cardiac surgery.