Effects of exercise on atrial natriuretic factor. Release mechanisms and implications for fluid homeostasis.

Atrial natriuretic factor is reported to be elevated during and immediately following exercise and is thought to play a role in fluid homeostasis and cardiovascular regulation. The predominant stimuli for atrial natriuretic factor release during exercise appear to be increases in atrial pressures or atrial distension, both of which are reported to increase with exercise. The intensity and perhaps duration of exercise also influence the magnitude of the atrial natriuretic factor response. It is not clear if the rise in plasma atrial natriuretic factor during exercise plays any role in altering renal function since high intensity exercise is typically associated with an antidiuresis. However, elevations in plasma atrial natriuretic factor may in part be responsible for the increase in urine flow reported when exercise is performed at low or moderate intensities. Atrial natriuretic factor also has vascular effects which may be important in buffering or moderating the blood pressure response to exercise. The atrial natriuretic factor response to exercise and basal levels of the hormone are greatly elevated in patients who suffer from a variety of cardiovascular and pulmonary disease conditions. These elevated plasma atrial natriuretic factor values are associated with increases in atrial pressure and appear to be related to the severity of disease. Although much controversy exists regarding the renal and vascular effects of atrial natriuretic factor, the measurement of this hormone, particularly during exercise, may be of clinical value by providing an additional tool to evaluate patients and determine the effectiveness of various treatment regimens.