ABSTRACT
The effects of the embryonic environment on juvenile phenotypes are widely recognized. We investigated the effect of embryonic hypoxia on the cardiovascular phenotype of 4-year-old American alligators (Alligator mississippiensis). We hypothesized that embryonic 10% O2 preconditions cardiac function, decreasing the reduction in cardiac contractility associated with acute 5% O2 exposure in juvenile alligators. Our findings indicate that dobutamine injections caused a 90% increase in systolic pressure in juveniles that were incubated in 21% and 10% O2, with the 10% O2 group responding with a greater rate of ventricular relaxation and greater left ventricle output compared with the 21% O2 group. Further, our findings indicate that juvenile alligators that experienced embryonic hypoxia have a faster rate of ventricular relaxation, greater left ventricle stroke volume and greater cardiac power following β-adrenergic stimulation, compared with juvenile alligators that did not experience embryonic hypoxia. When juveniles were exposed to 5% O2 for 20 min, normoxic-incubated juveniles had a 50% decline in left ventricle maximal rate of pressure development and maximal pressure; however, these parameters were unaffected and decreased less in the hypoxic-incubated juveniles. These data indicate that embryonic hypoxia in crocodilians alters the cardiovascular phenotype, changing the juvenile response to acute hypoxia and β-adrenergic stimulation.
FOOTNOTES
Competing interests
The authors declare no competing or financial interests.
Author contributions
Conceptualization: B.S., J.L.C., R.M.E., J.W.H., D.A.C.; Methodology: B.S., J.L.C., J.W.H.; Formal analysis: B.S., J.L.C., D.A.C.; Investigation: D.A.C.; Resources: R.M.E., D.A.C.; Data curation: D.A.C.; Writing - original draft: B.S., J.W.H., D.A.C.; Writing - review & editing: B.S., J.L.C., R.M.E., J.W.H., D.A.C.; Visualization: D.A.C.; Supervision: J.W.H., D.A.C.; Project administration: D.A.C.; Funding acquisition: D.A.C.
Funding
This study was supported by a National Science Foundation CAREER award IBN IOS-1755187 to D.A.C.
- Received April 15, 2019.
- Accepted September 16, 2019.
- © 2019. Published by The Company of Biologists Ltd
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