Abstract
The effect of thyroid hormone pretreatment on intracellular potentials recorded from
isolated rat atria has been investigated. Recordings were made by conventional intracellular
recording techniques and it was found that in spontaneously beating right atria from
thyroxine treated rats both the resting membrane potential and the 95% repolarization
times were reduced. Atria from treated animals beat much faster than those from controls
but only part of the changes seen resulted directly from this for both variables were
statistically significantly reduced in treated atria driven at 240 beats/minute i.e.
above the maximum spontaneous rate observed.
It was suggested that the electrophysiological changes seen might partially account
for the arrhythmias associated with hyperthyroidism.
Key words
Thyroxine - Atria - Intracellular Potentials - Tachycardia
1 Present address: Faculty of Pharmacy, Mahidol University, Phyathai, Sri-Ayuthaya
Road, Bangkok, Thailand
2 Present address: Department of Pharmacology, Faculty of Medicine, University of British
Columbia, Vancouver 8,
Canada
