Submitted on December 11, 2007
Accepted on March 17, 2008
Determination of Plasma and Urinary Angiotensinogen Levels in Rodents by Newly Developed ELISA
Hiroyuki Kobori1*, Akemi Katsurada1, Kayoko Miyata1, Naro Ohashi1, Ryousuke Satou1, Toshie Saito1, Yoshiaki Hagiwara2, Kazuya Miyashita2, and L. Gabriel Navar1
1 Department of Physiology, and Hypertension and Renal Center of Excellence, Tulane University Health Sciences Center, New Orleans, Louisiana, United States
2 Immuno-Biological Laboratories Co., Ltd., Fujioka, Gunma, Japan
* To whom correspondence should be addressed. E-mail: hkobori{at}tulane.edu.
We recently reported that urinary excretion rates of angiotensinogen provide a specific index of the intrarenal renin-angiotensin system status in angiotensin II-dependent hypertensive rats. Angiotensinogen concentrations in mouse plasma are thought to be much lower than that in rat plasma; however, detailed information is deficient due to lack of direct quantitative measurements of rodent angiotensinogen. To elucidate this issue, we have developed a quantitative method for measurement of rodent angiotensinogen using a sandwich-type ELISA. The standard curve for mouse and rat angiotensinogen exhibited a high linearity at 0.16-10 and 0.08-5 ng/mL, respectively with correlation coefficients better than 0.99. While plasma angiotensinogen concentrations of HIGA mice (IgA nephritis model animals, 1308+/-47 ng/mL, N=10) were lower than that of control BALB/c mice (1620+/-384, N=12), urinary angiotensinogen concentrations of HIGA mice (14.6+/-1.5 ng/mL, N=34) were higher than that of BALB/c mice (4.6+/-0.1, N=2). In a similar manner, while plasma angiotensinogen concentrations of Zucker diabetic fatty (ZDF) obese rats (type 2 diabetic model animals, 1789+/-50 ng/mL, N=5) were lower than that of control ZDF lean rats (2296+/-47, N=5), urinary angiotensinogen concentrations of ZDF obese rats (88.2+/-11.4 ng/mL, N=15) were higher than that of ZDF lean rats (31.3+/-1.9, N=15). These data indicate that plasma and urinary angiotensinogen concentrations are less in mice than rats. However, these data suggest that urinary angiotensinogen levels are different from plasma angiotensinogen levels in rodents. The development of rodent angiotensinogen ELISA allows quantitative comparisons in mouse and rat angiotensinogen levels in models of hypertension, and cardiovascular and kidney diseases.
