AJP - Regulatory, Integrative and Comparative Physiology, Vol 239, Issue 3 254-R258, Copyright © 1980 by American Physiological Society
Temperature effects on ventilation and acid-base balance of the green turtle
D. R. Kraus and D. C. Jackson
Ventilation (VE), pulmonary gas exchange (MO2 and MCO2), and arterial
acid-base status (pH and PaCO2) were measured in immature green turtles.
Chelonia mydas, equilibrated at 15, 25, and 35 degrees C. From 25 to 35
degrees C, pH decreased by 0.0134 U/degrees C and PaCO2 increased from 30.1
+/- 1.1 to 46.0 +/- 2.4 Torr (mean +/- SE, n = 8) in conformity with
results from other ectotherms. From 15 to 25 degrees C, however, pH fell on
the average by 0.06 U/degrees C but the change was not significant. PaCO2
rose over this range from 25.3 +/- 1.6 to 30.1 +/- 1.1 Torr. Calculated
plasma [HCO3-], 27-28 meq/l, did not change over the entire temperature
range. Both VE and MO2 increased with temperature, but the ratio, VE/MO2
(the air convection requirement), fell with temperature (1.01 +/- 0.10
l/mmol at 35 degrees C, 0.64 +/- 0.03 l/mmol at 25 degrees C, and 0.45 +/-
0.04 l/mmol at 15 degrees C). We conclude that the green turtle adheres to
the typical ectotherm blood acid-base pattern over their usual temperature
range (25-35 degrees C), but that pH control deviates from this pattern at
temperatures below this range.
