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The Formula 1 Heart of the Etruscan Shrew Suncus etruscus : Using the Extreme to Exemplify Basic Principals in Cardiovascular Physiology
Author(s) -
Harris Michael B.,
Flores Phillip H.,
Francis Rohin
Publication year - 2018
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2018.32.1_supplement.629.17
Subject(s) - suncus , diastole , cardiovascular physiology , cardiac cycle , myocyte , cardiac muscle , cardiology , medicine , biology , blood pressure
Modern teaching in physiology is greatly enhanced by strategies such as case‐based instruction. A variant of this employs a comparative approach to illustrate basic physiological principles and promote mechanistic thinking. As with clinical cases, examples from comparative physiology can illustrate dramatic responses of physiological systems under extreme stresses, or specializations, optimizations and integration of physiological processes underlying extreme performance. A typical course in physiology considers the structure and function of muscles, and specializations particular to cardiac muscle. Characteristics of cardiac myocytes are illustrated which underlie myogenic pacemakers and syncytial propagation of cardiac action potential between adjacent cells. Considered are patterns of excitation distribution from cardiac pacemakers through the conducting system leading to precise patterns of muscle contraction ensuring synchronized blood flow through the chambers of the heart. Mechanisms coupling changes in membrane polarization to myofibril cross‐bridge formation and ion fluxes and channel properties integral to muscle contraction, relaxation and refractory periods are all described. Integral to these concepts are the temporal durations of basic physiological processes resulting in a coordinated pattern of autorhythmic systole and diastole, and the capacities for autonomic modulation of the heart to match cardiac output to metabolic demands. These basic principles are commonly only described in relation to humans, and resulting in a healthy heart beating at 72 beats per minute. The Etruscan Shrew, Suncus etruscus , presents as a compelling comparative example, having a heart rate as high as 1500 bpm. We consider the shrew to illustrate basic physiological mechanisms, what is known, what can be predicted and what mysteries remain as to the capacities necessary to accommodate extreme cardiac cycle frequencies approaching 25 Hz. Support or Funding Information Work reported in this publication was supported by the National Heart Lung and Blood Institute and National Institute of General Medical Sciences of the National Institutes of Health under awards 1R15HL126105 and 1SC2GM112570. The work is solely the responsibility of the authors and does not necessarily represent the official view of the National Institutes of Health or any other funding body. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .