This technique is used to examine intrinsic properties of 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 cannula is connected to a pressure reservoir or a pressure servo controler.
- The distal cannula is closed with a stopcock ("blind sac" preparation, no luminal flow).
- 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.
- Void of neural and circulating influences
- Constant transmural pressure, no luminal flow - minimizes changes in shear forces
- Direct visualization of the blood vessel
- Allows precise control of transmural pressure - myogenic responses can be studied
- Endothelium can be removed (e.g. air perfusion) to examine endothelium-independent responses
- Vascular segment is isolated from the surrounding tissue
- Drugs cannot be applied from the luminal side without inflicting flow
- Adventitial side drug application prevents larger molecules (e.g. peptides) from reaching the endothelium - endothelium-dependent effects of bradykinin, substance P, angiotensin II cannot be studied
- Smaller arterioles can are increasingly challenging to preparate