Integrative Cardiovascular Laboratories

Flow-Induced Dilation

 

 

 

 

 

 

 

This technique is used to examine flow-induced dilation in isolated resistance vessels (arterioles and small arteries).

1. The blood vessel is isolated using a stereo microscope, microscissors and microforcepses.
2. The vessel is mounted on two glass cannulas in a microvessel chamber and secured with a ligature.
3. The proximal and distal cannula each is connected to a pressure reservoir or a pressure servo controler.
4. A microflowmeter is also connected inline with the pressure servo controlers.
5. The chamber is superfused with heated and oxygenated buffer solution.
6. The chamber is mounted on a stage of a microscope (inverted or regular depending on the chamber type) connected to a video camera.
7. The signal from the video camera is leading to the video card of a personal computer equipped with a video dimensioning software.
8. The vessel is visualized on the computer monitor and internal diameter is measured by adjusting the guides superimposed by the software.
9. The software also captures images (1frame/sec), which are stored as digital files for documentation.
10. During the equilibration period the flow is the same on both sides of the vessel.
11. To establish graded levels of luminal flow (0-50µL/min in 5-10µL/min increments) the proximal and distal pressures adjusted in an equal and opposite manner.

 

 

 

 

 

 

 

 

 

Advantages:

1. Void of neural and circulating influences
2. Constant midpoint transmural pressure, no myogenic changes
3. Direct visualization of the blood vessel
4. Allows precise control of flow
5. Drugs can be administered from the endothelial side
6. Endothelium can be removed (e.g. air perfusion) to examine endothelium-independent responses

Limitations:

1. Vascular segment is isolated from the surrounding tissue
2. Smaller arterioles can are increasingly challenging to preparate