Prior to starting an experiment on tubular tissues using the DMT Myographs
, it is highly recommended that you carry out the normalization process using the ADInstruments Normalization module.
The normalization calculation and procedure was devised, validated and published by Prof. Michael Mulvany using rat mesenteric arteries. This procedure allows the user the ability to define the pre-experimental conditions and thereby standardize each piece of tissue. There are three major reasons for normalizing elastic tissue:
1. Size of elastic structures (i.e. such as vessels) can only have meaning if the conditions are clearly defined.
2. The sensitivity of muscular preparations to agonists is dependent on the degree of stretch, therefore the experimental conditions, such as pretension of the tissue, need to be clearly defined.
3. As the active response of a tissue is dependent on the extent of stretch (according to the active tensioninternal circumference relation), it is useful to set tissues to an internal circumference which gives the maximum response, according to the amount of muscular tissue in the sample.
Mulvany conducted the initial validation studies of the normalization procedure using rat mesenteric arteries and found that the best experimental conditions were obtained if one defines the vessel size as being the size (internal circumference) when the vessel is fully relaxed and under a transmural pressure of 100 mmHg. In determining and setting the internal circumference in relation to a set pressure means that each tissue can be standardized. This standardization takes into account the amount of elastic tissue (smooth muscle) mounted on the wire myograph. Therefore the aim of the normalization procedure is to determine, for a vessel mounted on the myograph, the internal circumference (IC100) at which the vessel would have if relaxed and under a transmural pressure of 100 mmHg. (N.B. In earlier published literature, IC100 was referred to as L100).
For further details see Mulvany and Halpern, Circulation Research 1977, 41: 19-26
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