Evidence for an intrarenal renin-angiotensin system in the rainbow trout, Oncorhynchus mykiss.
Physiological and molecular approaches were used to investigate the existence of an intrarenal renin-angiotensin system (RAS) in rainbow trout. Inhibition of angiotensin-converting enzyme by captopril (5 x 10(-4 )M) rapidly decreased vascular resistance of the trunk of the trout, perfused at 19 mmHg, resulting in an increased perfusate flow rate and a decreased intrarenal dorsal aortic pressure. A profound diuresis occurred in the in situ perfused kidney and reflected both increased glomerular filtration rates and decreased water reabsorption (osmolyte reabsorption was unchanged). Renal and vascular parameters recovered once captopril treatment was stopped. Diuretic and vascular effects of captopril on the in situ trout kidney concur with an inhibition of known vasoconstrictor and antidiuretic actions of angiotensin II. However, at a higher perfusion pressure (28 mmHg), captopril had no effect on intrarenal aortic pressure or perfusate and urine flow rates, suggesting that the trout intrarenal RAS is activated by low perfusion pressures/flows. Existence of the renal RAS in trout was further supported by evidence for angiotensinogen gene expression in kidney as well as liver.
Brown
J A
JA
School of Biological Sciences, Hatherly Laboratories, University of Exeter, Exeter EX4 4PS, United Kingdom. J.A.Brown@exeter.ac.uk
Paley
R K
RK
Amer
S
S
Aves
S J
SJ
D000804:Angiotensin II / Q000235:genetics; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000808:Angiotensinogen / Q000235:genetics; D000818:Animals; D015152:Blotting, Northern; D002216:Captopril / Q000494:pharmacology; D018076:DNA, Complementary; D005260:Female; D015870:Gene Expression / Q000502:physiology; D005919:Glomerular Filtration Rate / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D007668:Kidney / Q000187:drug effects / Q000502:physiology*; D008297:Male; D017686:Oncorhynchus mykiss / Q000502:physiology*; D010477:Perfusion; D011312:Pressure; D012333:RNA, Messenger / Q000032:analysis; D012079:Renal Circulation / Q000187:drug effects / Q000502:physiology; D012084:Renin-Angiotensin System / Q000187:drug effects / Q000502:physiology*; D014556:Urine
D000806:Angiotensin-Converting Enzyme Inhibitors; D018076:DNA, Complementary; D012333:RNA, Messenger; D000808:Angiotensinogen; D000804:Angiotensin II; D002216:Captopril