Natriuretic and diuretic effects of endothelin in isolated perfused rat kidney

In an attempt to clarify the pathophysiological role of endothelin (ET), a novel vasoconstrictor peptide, we administered this peptide into the medium of isolated perfused rat kidney (IPK). ET increased renal vascular resistance by 53%, and reduced inulin clearance by 29% in IPK at a higher concentration of 500 PM. However, fractional excretion of sodium and urine flow rate were increased by 160% and 109%, respectively. These findings suggest that ET modulates the tubular sodium reabsorption as well as the renal hemodynamics.