5.23 Discussion of the Case
Spontaneously beating atria were isolated from rats and suspended in a suitable bath
solution. Heart rate and contractile force were continuously measured, discarding
those showing arrhythmia. Suitable pieces of the intact organs were inserted into
ESR tube for the analysis without previous manipulation. The spectrum of these
samples is reported in Fig. 5.17a and compared with that of the same pieces of rat
atria, pulverized under liquid nitrogen (Fig. 5.17b). The spectra obtained simply by
inserting the pieces of the beating organs between the magnet expansions into the
resonant cavity, without any manipulation, showed the presence of a very weak
signal at g = 2.00. Pulverized atria showed instead a much more intense signal at
the same resonant magnetic field.
These results suggest that the presence of paramagnetic centers is fully due to
artifacts generated by the grinding of tissues.
(a)
(b)
Fig. 5.17 a ESR spectrum of rat atria frozen in liquid nitrogen and b the same while pulverized
under liquid nitrogen [15]
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5 The Symmetry Properties Describe the Electronic Structure …