Related Experiment Video
Updated: Oct 14, 2025
A Methodological Approach to Non-invasive Assessments of Vascular Function and Morphology
Published on: February 7, 2015
A novel evaluation of endothelial dysfunction ex vivo: "Teaching an Old Drug a New Trick"
Lexiao Jin1,2, Daniel J Conklin1,2,3,4,5
1American Heart Association-Tobacco Regulation and Addiction Center, University of Louisville, Louisville, Kentucky, USA.
Insights
A novel L-NAME PE Contraction Ratio (PECR) assay effectively measures endothelium dysfunction (ED) by correlating with acetylcholine-induced relaxation. This validated method offers a robust tool for assessing vascular health and toxicity mechanisms.
Area of Science:
- Vascular Biology and Toxicology
- Cardiovascular Research
- Endothelium Function Assays
Background:
- Cardiovascular disease (CVD) is a leading global cause of death, often originating from endothelium dysfunction (ED).
- Existing methods for assessing ED can be complemented by novel, robust assays.
- Endothelium dysfunction underlies conditions such as hypertension, thrombosis, and atherosclerosis.
Purpose of the Study:
- To develop and validate a novel assay, the L-NAME PE Contraction Ratio (PECR), for quantifying endothelium dysfunction.
- To assess the correlation between the PECR and acetylcholine-induced relaxation (ACh %) in isolated murine aorta.
- To evaluate the PECR's utility in identifying vascular toxicity and its species-specific dependence.
Main Methods:
- Isolated murine aorta preparations were used to measure phenylephrine-induced contractions (PE) with and without L-NAME.
- The L-NAME PE Contraction Ratio (PECR) was calculated as 'PE Tension post-L-NAME' divided by 'PE Tension pre-L-NAME'.
- Retrospective analyses of published data and cross-species validation in rat aorta were performed.
Main Results:
- A strong positive correlation was observed between PECR and ACh % in naïve aortas (r² = 0.91).
- PECR correlated positively with ACh % in mice exposed to various agents, decreasing with established ED.
- The PECR assay demonstrated species-specific differences and reflected nitric oxide synthase (NOS) function.
Conclusions:
- The PECR is a robust and validated measure of endothelium dysfunction and vascular toxicity.
- This novel assay provides mechanistic insights into vascular dysfunction and complements existing ED tests.
- The PECR assay offers a valuable tool for cardiovascular research and toxicology studies.
Abstract:
Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide. Many CVDs begin with endothelium dysfunction (ED), including hypertension, thrombosis, and atherosclerosis. Our assay evaluated ED in isolated murine aorta by quantifying phenylephrine-induced contractions (PE) in the presence of L-NAME, which blocked acetylcholine-induced relaxation (ACh %; >99%). The "L-NAME PE Contraction Ratio" (PECR) was defined as: "PE Tension post-L-NAME" divided by "PE Tension pre-L-NAME." We hypothesized that our novel PE Contraction Ratio would strongly correlate with alterations in endothelium function. Validation 1: PECR and ACh % values of naïve aortas were strongly and positively correlated (PECR vs. ACh %, r2 = 0.91, n = 7). Validation 2: Retrospective analyses of published aortic PECR and ACh % data of female mice exposed to filtered air, propylene glycol:vegetable glycerin (PG:VG), formaldehyde (FA), or acetaldehyde (AA) for 4d showed that the PECR in air-exposed mice (PECR = 1.43 ± 0.05, n = 16) correlated positively with the ACh % (r2 = 0.40) as seen in naïve aortas. Similarly, PECR values were significantly decreased in aortas with ED yet retained positive regression coefficients with ACh % (PG:VG r2 = 0.54; FA r2 = 0.55). Unlike other toxicants, inhaled AA significantly increased both PECR and ACh % values yet diminished their correlation (r2 = 0.09). Validation 3: To assess species-specific dependence, we tested PECR in rat aorta, and found PECR correlated with ACh % relaxation albeit less well in this aged and dyslipidemic model. Because the PECR reflects NOS function directly, it is a robust measure of both ED and vascular dysfunction. Therefore, it is a complementary index of existing tests of ED that also provides insight into mechanisms of vascular toxicity.
