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Pressure overload surgery does not induce cardiac fibrosis in the American alligator
Author(s) -
Campbell Colin,
Owerkowicz Tomasz,
Eme John,
Blank Jason,
Hicks James
Publication year - 2011
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.25.1_supplement.858.12
Subject(s) - ventricle , trichrome stain , pressure overload , cardiology , muscle hypertrophy , medicine , fibrosis , volume overload , ventricular hypertrophy , left ventricular hypertrophy , anatomy , heart failure , cardiac hypertrophy , blood pressure , immunohistochemistry
In the dual aortic arch system of crocodilians, the right aorta emerges from the left ventricle, and the left aorta (LAo) exits the right ventricle. The LAo allows for potential pulmonary bypass (R‐L shunt). Surgical ablation of the LAo has been used to test the functional significance of R‐L shunting in alligators. In earlier studies, LAo ablation caused greater (+65%) ventricular mass, higher DNA content and doubled peak systolic pressures, but the exact nature of hypertrophy has not been described. We compared ventricular cross‐sections from juvenile alligators who had undergone LAo ablation or sham surgery. Animals were either sedentary or exercised every other day. Histologic assessment with Masson's trichrome stain showed normal myocardial growth, with minimal (<2%) fibrotic tissue accumulation, and no significant difference between treatment groups (n=5). Physiologic (muscular) hypertrophy is an expected response to regular exercise, and pathologic (fibrotic) hypertrophy is seen in mammals faced with chronic pressure overload (e.g., aortic banding). Our results suggest alligators are capable of impressive cardiac plasticity, without suffering pathologic fibrosis in the myocardium. This phenomenon parallels the magnitude of post‐prandial cardiac hypertrophy in pythons. Molecular mechanisms behind myocardial growth capacity in reptiles remain to be elucidated. Funded by NSF IOB 00445680.