Electrical activation of the ventricular myocardium of the crocodile Crocodylus johnstoni: a combined microscopic and electrophysiological study

• Published in: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Vol. 123; no. 1; pp. 17 - 23
• Main Authors: Christian, E, Grigg, G.C
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.05.1999
• Subjects: Activation; Alligators and Crocodiles - anatomy & histology; Alligators and Crocodiles - physiology; Animals; Crocodile; Crocodylus johnstoni; Depolarization; Electrical; Electroencephalography; Electrophysiology; Heart; Heart - anatomy & histology; Heart Conduction System - physiology; Heart Septum - anatomy & histology; Heart Septum - physiology; In Vitro Techniques; Medical Illustration; Myocardial; Septum; Ventricle; Ventricular Function - physiology; Depolarization; Heart; Crocodile; Myocardial; Septum; Activation; Electrical; Ventricle
• ISSN: 1095-6433; 1531-4332
• DOI: 10.1016/S1095-6433(99)00024-0

We mapped the sequence of ventricular depolarization in the crocodile Crocodylus johnstoni. We also attempted to find specialized conduction tissue within the ventricular myocardium. Electrical recordings with miniature multi-point electrodes revealed two strands of rapidly conducting tissue (channels) within the interventricular septum, suggestive of conductive tissue pathways. From these septal channels, wavefronts of excitation swept around each ventricle. Electrical recordings did not indicate that there was conductive tissue in the wall of either ventricle. Similarly, microscopic studies of the septal channels provided no indication of specialized conductive tissue. We suggest that the channels of early septal depolarization provide the crocodile heart with a high speed depolarization pathway functionally analogous to a rudimentary conductive system.