Dissociation of Bradycardia and Arterial Constriction during Diving in the Seal Phoca vitulina

Bradycardia associated with diving in the harbor seal has been dissociated from the arterial constrictor response by intracardiac pacing. Development of arterial constriction does not depend upon the development of bradycardia. During pacing, arterial constriction continues in the absence of bradyca...

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Bibliographic Details
Published in:Science
Main Authors: Murdaugh, H. V., Cross, Carroll E., Millen, J. Eugene, Gee, J. Bernard L., Robin, Eugene D.
Format: Article in Journal/Newspaper
Language:English
Published: American Association for the Advancement of Science (AAAS) 1968
Subjects:
harbor seal
Phoca vitulina
Online Access:http://dx.doi.org/10.1126/science.162.3851.364
https://www.science.org/doi/pdf/10.1126/science.162.3851.364
Description
Summary:Bradycardia associated with diving in the harbor seal has been dissociated from the arterial constrictor response by intracardiac pacing. Development of arterial constriction does not depend upon the development of bradycardia. During pacing, arterial constriction continues in the absence of bradycardia. Increases in heart rate to values greater than 120 beats per minute during a dive produce a progressive decrease in mean aortic pressure, which suggests that one major function of bradycardia is to reduce cardiac output, thus matching left ventricular output to the restricted vascular bed and decreased venous return associated with diving.

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