Journal of Applied Physiology, Vol 62, Issue 2 459-463, Copyright © 1987 by American Physiological Society
Pulmonary function of the green sea turtle, Chelonia mydas
R. N. Gatz, M. L. Glass and S. C. Wood
Lung volumes, oxygen uptake (VO2), end-tidal PO2, and PCO2, diffusing
capacity of the lungs for CO (DLCO), pulmonary blood flow (QL) and
respiratory frequency were measured in the green sea turtle (Chelonia
mydas) (49-127 kg body wt). Mean lung volume (VL) determined from helium
dilution was 57 ml/kg and physiological dead space volume (VD) was about
3.6 ml/kg. QL, determined from acetylene uptake during rebreathing,
increased in proportion to VO2 with temperature. Therefore, constant O2
content difference was maintained between pulmonary arterial and venous
blood. DLCO, measured using a rebreathing technique, was 0.04 ml X kg-1 X
min-1 X Torr-1 at 25 degrees C. Several cardiopulmonary characteristics in
C. mydas are advantageous to diving: large tidal volume relative to
functional residual capacity promotes fast exchange of the alveolar gas
when the turtle surfaces for breathing: and the concomitant rise of
pulmonary blood flow and O2 uptake with temperature assures efficient O2
transport regardless of wide temperature variations encountered during
migrations.
