1. Aortic smooth muscle sodium efflux was studied in normal rats undergoing salt restriction or salt loading.
2. Sodium efflux rate constant was not changed by salt loading but fell significantly with salt restriction. This change was not associated with a fall in blood pressure.
3. These studies show that smooth muscle sodium transport can be influenced by dietary salt intake but do not support the concept that salt loading leads to the inhibition of the vascular smooth muscle sodium pump.