Affiliation:
1. Masonic Medical Research Laboratory, Utica, New York 13501
Abstract
The electrical threshold of A-V nodal cells of isolated rabbit heart preparations was estimated by techniques which permitted stimulation and recording through the same micropipette. Cells within the node were significantly less excitable than adjacent atrial and ventricular tissues; thresholds exceeded 5 x 10
-6
amp in some instances. Recovery of excitability was delayed well beyond repolarization; in cells of the midnodal region, "diastolic" threshold was not attained until 0.2 to 0.5 seconds after restoration of resting membrane potential. A cumulative effect of frequency upon excitability (fatigue) was demonstrated. At high driving rates, the lag in recovery was further delayed, and the late diastolic threshold was increased. Responses to single-cell stimulation indicate that summation may be an important feature of propagation within the node.
Publisher
Ovid Technologies (Wolters Kluwer Health)
Subject
Cardiology and Cardiovascular Medicine,Physiology
Reference18 articles.
1. HOFFMAN B. F. AND CBANEFIELD P. F.: Electrophysiology of the Heart. New York Mc-Graw-Hill Book Co. Inc. 1960.
2. Effects of calcium ions and local anaesthetics on electrical properties of Purkinje fibres
3. KRAYEH O. MANDOKI J. J. AND MENDEZ C : Studies on veratrum alkaloids: XVI. The action of epinephrine and of veratramine on the functional refractory period of the auriculoventricular transmission in the heartlung preparation of the dog. J. Pharmacol. Exptl. Therap. 10 3 : 142 1951.
4. Observations upon conduction in the mammalian heart; A-V conduction;LEWIS T.;Heart,1925
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