An impoant non-respiratory function of Lungs is:
Anion balance
Sodium balance
Potassium balance
Calcium balance
Lung has large amounts of angiotensin conveing enzyme which is located on the surface of endothelial cells of the pulmonary capillary. This enzyme conves the inactive decapeptide angiotensin I into aldosterone stimulating octapeptide angiotensin II. This angiotensin II stimulates the production of aldosterone which increase sodium resoption, thereby maintaining sodium balance. Ref: Pulmonary Physiology, Lange Physiology Seires, 6th Edition, Pages 215-226.