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Removal of cardiac shunt impairs growth and causes ventricular hypertrophy in American alligator
Author(s) -
Eme John,
Gwalthney June,
Owerkowicz Tomasz,
Blank Jason M.,
Hicks James W.
Publication year - 2008
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.22.1_supplement.1239.26
Subject(s) - medicine , cardiology , ventricle , cardiac output , shunting , shunt (medical) , alligator , cardiac ventricle , anatomy , biology , hemodynamics , paleontology
Reptilian cardiac shunting is hypothesized to confer a fitness advantage via physiological functions including inducing hypometabolism, aiding recovery from metabolic acidosis and facilitating digestion. Elimination of cardiac shunt has not previously been shown to reduce fitness. Crocodilians possess a unique reptilian cardiac anatomy (fully‐divided ventricle) that allows surgical elimination of right‐to‐left cardiac shunt. We altered the outflow tract of hatchling alligators by occluding the left aorta proximal and distal to the foramen of Panizza. Surgical and sham groups (n=36 each) were subsequently split into three exercise regimes: run, swim and sedentary (n=24 each). Run and swim groups were exercised to exhaustion using a treadmill or swim flume every other day for 15 months, and growth was monitored. Elimination of cardiac shunt led to significantly lower mean body mass of surgical alligators (~10%), but resulted in a significantly larger ventricular mass (~65%). Maximum aerobic capacity of alligators was increased (~15%) by exercise training (both running and swimming), but not affected by shunt elimination. We suggest cardiac shunting has adaptive significance to crocodilians by allowing faster growth and reducing cardiac work. Funded by NSF IOB 04445680 to JWH.