This technique is used to examine flow-induced dilation in isolated resistance vessels (arterioles and small arteries).
- The blood vessel is isolated using a stereo microscope, microscissors and microforcepses.
- The vessel is mounted on two glass cannulas in a microvessel chamber and secured with a ligature.
- The proximal and distal cannula each is connected to a pressure reservoir or a pressure servo controler.
- A microflowmeter is also connected inline with the pressure servo controlers.
- The chamber is superfused with heated and oxygenated buffer solution.
- The chamber is mounted on a stage of a microscope (inverted or regular depending on the chamber type) connected to a video camera.
- The signal from the video camera is leading to the video card of a personal computer equipped with a video dimensioning software.
- The vessel is visualized on the computer monitor and internal diameter is measured by adjusting the guides superimposed by the software.
- The software also captures images (1frame/sec), which are stored as digital files for documentation.
- During the equilibration period the flow is the same on both sides of the vessel.
- 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.
- Void of neural and circulating influences
- Constant midpoint transmural pressure, no myogenic changes
- Direct visualization of the blood vessel
- Allows precise control of flow
- Drugs can be administered from the endothelial side
- Endothelium can be removed (e.g. air perfusion) to examine endothelium-independent responses
- Vascular segment is isolated from the surrounding tissue
- Smaller arterioles can are increasingly challenging to preparate