Figure 148

Endothelin (ET) is a potent renal vasoconstrictor. Endothelin (ET) is a 21 amino acid peptide of which three isoforms—ET-1, ET-2 and ET-3—have been described, all of which have been shown to be present in renal tissue. However, only the effects of ET-1 on the kidney have been clearly elucidated. ET-1 is the most potent vasoconstrictor known. Infusion of ET-1 into the kidney induces profound and long lasting vasoconstriction of the renal circulation. A, The appearance of the rat kidney during the infusion of ET-1 into the inferior branch of the main renal artery. The lower pole of the kidney perfused by this vessel is profoundly vasoconstricted and hypoperfused. B, Schematic illustration of function in separate populations of glomeruli within the same kidney. The entire kidney underwent 25 minutes of ischemia 48 hours before micropuncture. Glomeruli I are nephrons not exposed to endothelin antibody; Glomeruli II are nephrons that received infusion with antibody through the inferior branch of the main renal artery. SNGFR—sin-gle nephron glomerular filtration rate; PFR—glomerular renal plasma flow rate. (From Kon et ai. [4]; with permission.)

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