Key result
Intraperitoneal injection of atropine (5mg/kg) in young chicks abolished the variation of RR and PQ intervals and inverted the T wave, indicating parasympathetic control of cardiac electrical activities.
Why the study?
Does atropine alter ECG parameters and T wave polarity in unrestrained chicks?
Does atropine alter ECG parameters and T wave polarity in unrestrained chicks?
In unrestrained chicks, parasympathetic activity controls both SA-nodal pacemaker cells and ventricular electrical activities, as evidenced by atropine-induced T wave inversion and abolition of RR and PQ interval variations.
Answers are grounded in this paper and cite their sources.
Atropine-induced ECG changes in chicks support parasympathetic ventricular control; hypothesis-generating for comparative electrophysiology with no clinical translation yet.
Chick electrocardiogram (ECG) was recorded using a pair of bipolar silver electrodes surgically fixed to the right clavicle and the sternal crest. Background noises were canceled by calculating the average of cardiac electrical activity of each beat. PQ interval was constantly longer when RR interval was prolonged, while QT interval was not altered when RR interval was changed. The variation of both RR interval and PQ interval was abolished by intraperitoneal injection of atropine (5mg/kg). Atropine inverted T wave, which suggested that the electrical activities of cardiac ventricular cells as well as those of pacemaker SA-nodal cells is under the control of the parasympathetic nerve in control chicks.
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Toyoda et al. (1999) studied Healthy (n=6). Atropine vs. Baseline (pre-injection) was evaluated on ECG wave parameters (RR interval, PQ interval, T wave polarity). Intraperitoneal injection of atropine (5mg/kg) in young chicks abolished the variation of RR and PQ intervals and inverted the T wave, indicating parasympathetic control of cardiac electrical activities.
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