Effects of left atrialadistension with exercise on α-human atrial natriuretic peptide(α-hANO) and relationship between α-hANP and exercise capacity

To assess the effects of left atrial distension with exercise on α-hANP and to evaluate the relationship between α-hANP and exercise tolerance, cardiopulmonary exercise testing was performed in 23 patients with prior myocardial infarction. The patients exercise on a bicycle ergometry until their exhausion. Left atrial diameter (LAD) increased significantly (P＜0.01) from 31.4±6.4 to 33.3±7.8mm, and α-hANP also increased significantly (p＜0.001) from 84±51 to 129±75pg/ml. Increments of LAD with exercise by LAD at rest (%Δ LAD) were positively sorrelated with changes in α-hANP (Δ α-hANP)(r＝0.43, p＜0.05). There was a negative correlation between peak V^^・_<O_2> and α-hANP after exercise (r＝-0.45, p＜0.05). Anaerbic threshold (AT) was also negatively correlated with α-hANP at rest (r＝-0.52, p＜0.02) and after exercise (r＝-0.56, p＜0.01). These indicate that exercise capacity is impaired in patients whose levels of α-hANP are elevated. Thus, left atrial distension may stimulate secreation of α-hANP. Cardiac patients with low exercise capacity have increased α-hANP before and after exercise.