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3.3 NORMALIZATION
The importance of normalizing the preparation is
three-fold:
1. Experiments with elastic preparations like
vessels can only have meaning if they are
performed under conditions where the size
is clearly defined.
2. Clearly defined conditions are required
in pharmacological experiments as the
sensitivity of preparations to agonists and
antagonists is dependent on the amount of
stretch.
3. The active response of a preparation is
dependent on the extent of stretch, which
makes it important to set the preparation
to an internal circumference giving maximal
response.
The aim of the normalization procedure is to stretch the segment to a so-called normalized internal
circumference (IC
1
): defined as a set fraction of the internal circumference (IC
100
) that a fully relaxed
segment would have at a specified transmural pressure. For small rat arteries the target transmural
pressure is typically 100 mmHg = 13.3 kPa.
