I'm sorry if i didn't get you right, but what exactly is ethically unaccepted?

The best method depends on which patient collective you want to measure and to which extend you want to or can use provocation tests.

On of the classic tests would be the patients reaction regrading post-occlusive reactive hyperaemia. You can measure the response by device like the O2C by LEA or have a look at the Periflux devices. The choice also depends on your potential needs for further possibilities like trans-dermal drug application etc.

You should specify whether you want to measure it in vivo or in vitro.

in vivo, in humans

that is ethically unaccepted!

I'm sorry if i didn't get you right, but what exactly is ethically unaccepted?

The best method depends on which patient collective you want to measure and to which extend you want to or can use provocation tests.

On of the classic tests would be the patients reaction regrading post-occlusive reactive hyperaemia. You can measure the response by device like the O2C by LEA or have a look at the Periflux devices. The choice also depends on your potential needs for further possibilities like trans-dermal drug application etc.

Another validated method is represented by FMD (flow-mediated dilation) of the brachial artery evaluated by ultrasound (see Coretti et al. JACC for details). We've been using it in the anaesthesia/IC setting as well with excellent results.

According to which type of vessel you want to explore you can use either echodoppler ultrasound (conductance vessels, usually brachial artery) or laser doppler flowmetry (for microvessels, usually cutaneous circulation). Whatever the vessel, you will need 2 provocative tests. The first one stimulate endothelium which induces Vascular smooth muscle relaxation (it is usually less than 5 min occlusion). The second directly stimulates vascular smooth muscle (usually NO donors). You can say that endothelium is modified only if the response to the first stimulation is changed while response to NO donor remains unchanged.

An EndoPat test (a digital peripheral arterial tonometry ) of the response to reactive hyperemia that reflects NO-dependent endothelial function can also be used . The association with traditional cardiovascular factors was shown in large epidemiological study.

The comparison of different methods is discussed: Circulation. 2012 Aug 7;126(6):753-67

Currently, the assessment of flow-mediated dilation in the brachial artery (FMD) is the most commonly used method to measure endothelial function in humans, mainly because of its sensitivity and noninvasive nature.

In animal studies you can evaluate endothelial function by “in vitro” essays using isolated arteries (aorta, mesenteric, etc.) and testing their response to drugs (for example, after contraction with phenylephrine, acetylcholine produces endothelium-dependent vascular relaxation while vasodilation produced by sodium nitroprusside is independent of endothelium)

Thank you for all answers.  What  would you advice for a laboratory (from blood sample) measurement of endothelial function? -

Von Willebrand factor is comonly used because ir is produced and released only  by endothelium. However, endothelium also produces a huge variery of substances with lots of actions. I would thus suggest to determine first which aspect of endothelial function you want to assess. 

eNOS，ET-1，NO

Unfortunately, there aren't great biomarkers of endothelial function.  Adhesion molecules (i.e. sVCAM-1) are an option, but circulating values may not represent what's going on at the vessel wall. F. Guerrero makes a very valid point - you need to decide which function is most important to you - damage, activation, thrombosisis generation, etc.  In the past, I have looked at sVCAM-1, sICAM-1, TNF-alpha, CRP, IL-6, and F2-isoprostanes.  These aren't all necessarily markers of endothelial function/dysfunction, necessarily, but they are involved in the the pathogenesis of ED and atherogenesis. Please let me know if you need more guidance once you decide which function you're looking at. 

I would like to  measuring endothelial dysfunction, and everything  which are involved in the pathogenesis of atherogenesis (I have experience with non invasive methods like PAD, FMD)

FMD is going to be your most robust measure of endothelial dysfunction.  I would then measure some marker of oxidative stress.  F2-isoprostanes are good, but they are very labor intensive to measure, so I would go with something like oxLDL.  You could also measure sVCAM-1 and sICAM-1, as well as any marker of inflammation you'd like (CRP, IL-6, TNF-alpha)... they all have their pros and cons so do your research and see what other people who have done similar studies to you have measured.  That should cover your bases -- though, in my experience, none of them provide particularly conclusive data.

I fully agree with you

Vilma,

You may consider checking endothelium-specific marker, endocan. In addition, I would recommend employing vascular activation/dysfunction-orientated multiplex (Millipore) analysis of your samples, if you have access to this system. 

Best regards

Gediminas

Thank you Gediminas, very interesting and usefull idea.

I think the best way to investigate the endothelium function in the isolated arteries is by using myography technique and measuring the cumulative curve-response to some agonists like ACh.

myography is good option