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Electrophysiology
of the ageing rabbit and cat sinoatrial node - a comparative study
Alings, A. M. W., Bouman, L. N.
Abstract
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Abstract
Intrinsic properties of the human sinoatrial (SA) node have been shown to
decline with age. In the present study we aimed at investigating the
underlying mechanisms of age-dependent changes in intrinsic cycle length and
sinoatrial conduction time. To this end, the cycle length and transmembrane
potentials of the SA nodes of rabbits (2 days-5.6 years) and cats (6 weeks-18
years) were recorded and nodal conduction was reconstructed. The size of the
SA nodes was measured in Sirius Red stained sections. Cycle length increases
with age in both the rabbit and cat SA node, and in both species cycle length
is dependent on diastolic depolarization rate and action potential duration.
Nodal action potential duration increases with age in both rabbit and cat,
whereas diastolic depolarization rate decreases in the cat only. The location
of the primary pacemaker is not related to age. With age, sinoatrial
conduction time increases in both species as a result of an enlargement of the
area with lowphase 0 upstroke velocities. The size of the SA node of adult
animals does not increase with age.
Reference
EUROPEAN HEART JOURNAL , 14(9):1278 1993
Updated January 2016
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