Urinary Renin Excretion is augmented in Chronic Angiotensin II‐infused Sprague‐Dawley Hypertensive Rats

Renin is upregulated in principal cells of the collecting ducts of angiotensin II (AngII)‐dependent hypertensive rats; however it remains unclear if increased distal nephron‐derived renin is secreted into the urine during AngII‐dependent hypertension. Urinary renin ( uRen ), angiotensinogen ( uAGT ) and AngII ( uAngI I) excretion was measured in chronic AngII‐infused male Sprague‐Dawley rats [80 ng/min, SC minipumps for 14 d, n=5] and control, sham‐operated rats [n=5]. Systolic blood pressures increased in the AngII rats by Day 5 and continued to increase throughout the study (Day 13; AngII: 175±10 vs. sham: 116±2 mm Hg). Although plasma renin activity was suppressed in the AngII‐infused rats (AngII: 0.3±0 vs. sham: 5.5±2 ng Ang I/ml/h); renin content in renal medullary tissues did not change (AngII: 10,564±1,476 vs. sham: 9,438±1,588 ng Ang I/h/mg; p=ns). Excretion of uAGT and uAngII increased in the AngII rats compared to sham rats, respectively [ uAGT (AngII:1107±106 vs. sham:60±26 ng/day); uAngII (AngII: 3813±431 vs. sham: 2080±361 fmol/day). Importantly, uRen excretion rate at Day 13 was markedly increased in the AngII rats (AngII: 9±3 vs. sham: 1±1×10 −5 Enzyme Units/day; p<0.05). Augmented uRen and uAGT may contribute to increased intrarenal AngII formation in AngII‐dependent hypertensive rats. NIH [IdeA (P20‐RR‐017659‐06), Tulane‐BIRCWH (K12HD043451)]; and AHA (09PRE2209079 and 09BGIA2280440).