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The Dual Wire Myograph Systems allow simultaneous, independent testing of two vessels with diameters of
60 μm to 3 mm. The vessels are mounted as ring preparations by threading them over two parallel stainless steel wires and securing the wires to two supports or "jaws".
»simultaneous testing of two vessels«
On the 410A Dual Wire Myograph System one support is attached to a precision micrometer, allowing manual control of vessel circumference and stretch. On the 510A the support is attached to a linear, motor-driven micrometer, allowing automated control of vessel circumference and stretch. The other support on both the 410A and the 510A is attached to a force transducer for measurements of force/tension development.
«the support is attached to a linear motor driven micrometer on model 510A»
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The preparation is mounted in a heated, 10 ml acid-resistant stainless steel chamber, which can be covered by a lid with ports for rapid suction/draining, refilling and oxygen supply.
The chamber can be divided for independent testing of each vessel. Glass windows in the base of the chamber allow morphological observations or fluorescence measurements on an inverted microscope to be made. Typically, the preparation is maintained in the heated chamber in a physiological salt solution at 37°C and bubbled with oxygen. Under these conditions, the vessels remain viable for at least 12 hours.
The two vessels can also be mounted in one common chamber by removing the divider. The vessels are thus exposed to identical conditions, such as the concentration of the compound of interest. This allows direct comparative studies of two vessels from treated/untreated conditions or patient samples e.g. diseased vs. healthy. It is thus possible to examine whether a given pathological state is associated with altered morphology or reactivity to endogenous compounds. It is also possible to examine whether drugs are able to normalize vessel reactivity.
»direct comparative studies of two vessels«
Following mounting and equilibration, the passive length-tension relationships of the vessels are determined, the so-called normalization. During the actual experiments, the circumferences of the vessels are kept constant, i.e. the vessels are examined under isometric conditions. Compounds are added directly to the chamber and vessel tension is monitored for possible contractile or relaxing effects.
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