Modulation by locally produced luminal angiotensin II of proximal tubular sodium reabsorption via an AT1 receptor.
The concentration of angiotensin II reported in proximal tubular fluid in anaesthetized rats is considerably higher than in plasma, indicating secretion of this peptide into the tubular lumen. Shrinking split-drop micropuncture was used to examine the effect of endogenous angiotensin on sodium and water absorption in the proximal convoluted tubule. Addition of losartan, a nonpeptide AT1 receptor blocker, to intratubular fluid increased fluid uptake by 15.7 +/- 3.9% (10(-5) M) and 24.7 +/- 9.4% (10(-4) M) whereas the AT2 inhibitor, PD123319 had no effect. We conclude that angiotensin II is secreted into proximal tubular fluid and, in the anaesthetized rat, is maintained at a concentration that inhibits sodium and water transport via AT1 receptors.
Department of Physiology, University of Melbourne, Parkville, Victoria, Australia.
S
S
Hiranyachattada
P J
PJ
Harris
D000803:Angiotensin I / Q000378:metabolism; D000804:Angiotensin II / Q000494:pharmacology*; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D001713:Biphenyl Compounds / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D007687:Kidney Tubules, Proximal / Q000187:drug effects* / Q000378:metabolism; D019808:Losartan; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011945:Receptors, Angiotensin / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D013777:Tetrazoles / Q000494:pharmacology
D057911:Angiotensin Receptor Antagonists; D001713:Biphenyl Compounds; D007093:Imidazoles; D011725:Pyridines; D011945:Receptors, Angiotensin; D013777:Tetrazoles; D000804:Angiotensin II; C073402:PD 123319; D000803:Angiotensin I; D012964:Sodium; D019808:Losartan