Acute effect of cigarette smoking on serum angiotensin-converting enzyme activity in normal man

The acute effect of cigarette smoking on serum angiotensin-converting enzyme activity was evaluated in 6 healthy subjects consisting of 4 non-smokers and 2 habitual smokers. Cigarette smoking resulted in rapid increases in serum converting enzyme activity in 5 of 6 subjects within 5 min. and the converting enzyme activity remained above the control value at 30 min. The increase in the enzyme activity of non-smokers was higher than that of habitual smokers at any time when the enzyme activity was determined. It is therefore suggested that cigarette smoke (or smoking) can cause the secretion of angiotensin-converting enzyme from the pulmonary endothelial cell, in which the enzyme may be produced, to the systemic circulation. It is also speculated that the increase in the enzyme activity may contribute to the initiation of cardiovascular changes associated with cigarette smoking.