The lung, whole-body metabolism and disease

It is well recognized that the lung has its own hormonally responsive endogenous metabolism. Less well recognized is the potential of the lung to influence and, in turn, be influenced by the homeostatic mechanisms of the body. It is suggested that the lung could modulate concentrations of circulating hormones and thereby play an indirect exogenous metabolic role in whole-body metabolism. Investigations of patients undergoing cardiopulmonary bypass as well as studies with the perfused rat lung suggest that the lung could make an important direct contribution to whole-body lactate and perhaps alanine production. The control of the endogenous and exogenous metabolism of the lung may be exerted through circulating hormones, substrates, blood gases and lung movement. Disorders of the lung or the whole body may disturb these relationships. In patients with chronic lung disease circulating blood metabolites are affected and conversely in diabetes there are effects on lung metabolism. The unified concept of lung/whole-body metabolism is discussed in relation to therapeutic approaches for the prevention and investigation of neonatal and adult respiratory distress syndromes.