Key result
Lowering the temperature caused a fall in diastolic membrane and action potentials and increased action potential duration in rabbit atrium fibers, with pacemaker fibers being most resistant.
Why the study?
Does lowering temperature and administering acetylcholine affect transmembrane potentials in single fibers of the rabbit atrium?
Does lowering temperature and administering acetylcholine affect transmembrane potentials in single fibers of the rabbit atrium?
Lowering temperature decreases membrane and action potentials in rabbit atrial fibers, while acetylcholine can restore propagated action potentials at low temperatures by increasing diastolic membrane potential.
Extends basic insights into hypothermic atrial electrophysiology; leaves open human translation and clinical relevance.
Lowering the temperature caused a fall in the diastolic membrane potential and action potential and an increase in the duration of the action potential in both pacemaker and nonpacemaker fibers of the rabbit atrium. Pacemaker fibers were the most resistant to cooling and continued to discharge at a temperature where all conducted action potentials and mechanical contractions had ceased. Acetylcholine (10 -7 Gm./ml.) administered at a low temperature when only pacemaker fibers were discharging, elicited propagated action potentials and contractions. This effect was associated with an increase in diastolic membrane potential towards that existing at a temperature of 30 C.
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Jean M. Marshall (1957) studied this question. Low temperatures was evaluated on Transmembrane potentials (diastolic membrane potential, action potential, and duration). Lowering the temperature caused a fall in diastolic membrane and action potentials and increased action potential duration in rabbit atrium fibers, with pacemaker fibers being most resistant.
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