A fluorogenic near-infrared imaging agent for quantifying plasma and local tissue renin activity in vivo and ex vivo
The renin-angiotensin system (RAS) is well studied for its regulation of blood pressure and fluid homeostasis, as well as for increased activity associated with a variety of diseases and conditions, including cardiovascular disease, diabetes, and kidney disease. The enzyme renin cleaves angiotensino...
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Published in | American journal of physiology. Renal physiology Vol. 303; no. 4; pp. F593 - F603 |
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Main Authors | , , , , , , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Physiological Society
15.08.2012
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Subjects | |
Online Access | Get full text |
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Summary: | The renin-angiotensin system (RAS) is well studied for its regulation of blood pressure and fluid homeostasis, as well as for increased activity associated with a variety of diseases and conditions, including cardiovascular disease, diabetes, and kidney disease. The enzyme renin cleaves angiotensinogen to form angiotensin I (ANG I), which is further cleaved by angiotensin-converting enzyme to produce ANG II. Although ANG II is the main effector molecule of the RAS, renin is the rate-limiting enzyme, thus playing a pivotal role in regulating RAS activity in hypertension and organ injury processes. Our objective was to develop a near-infrared fluorescent (NIRF) renin-imaging agent for noninvasive in vivo detection of renin activity as a measure of tissue RAS and in vitro plasma renin activity. We synthesized a renin-activatable agent, ReninSense 680 FAST (ReninSense), using a NIRF-quenched substrate derived from angiotensinogen that is cleaved specifically by purified mouse and rat renin enzymes to generate a fluorescent signal. This agent was assessed in vitro, in vivo, and ex vivo to detect and quantify increases in plasma and kidney renin activity in sodium-sensitive inbred C57BL/6 mice maintained on a low dietary sodium and diuretic regimen. Noninvasive in vivo fluorescence molecular tomographic imaging of the ReninSense signal in the kidney detected increased renin activity in the kidneys of hyperreninemic C57BL/6 mice. The agent also effectively detected renin activity in ex vivo kidneys, kidney tissue sections, and plasma samples. This approach could provide a new tool for assessing disorders linked to altered tissue and plasma renin activity and to monitor the efficacy of therapeutic treatments. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 J. Zhang and D. V. Preda contributed equally to this work. |
ISSN: | 1931-857X 1522-1466 |
DOI: | 10.1152/ajprenal.00361.2011 |