1. The effects of synthetic human and rat atrial peptides on sodium and potassium ion transport has been investigated in intact human erythrocytes.
2. The effects of these peptides have been tested on the active, sodium pump-dependent (ouabain-sensitive) and on the sodium-potassium cotransport system (bumetanide-sensitive) with 86Rb used as a tracer.
3. Human (α-ANP, 28 amino acids) or rat (atriopeptin III) atrial peptides, over a wide range of concentrations, did not influence the uptake of 86Rb in either the ouabain-sensitive or the bumetanide-sensitive transport system.
4. These results suggest that the natriuretic effect of the atrial peptides is not mediated through inhibition of the sodium pump or the loop-diuretic-sensitive Na-K cotransport.