LONG-TERM SUBMERGENCE AT 3-DEGREES-C OF THE TURTLE CHRYSEMYS-PICTA-BELLII IN NORMOXIC AND SEVERELY HYPOXIC WATER .3. EFFECTS OF CHANGES IN AMBIENT PO-2 AND SUBSEQUENT AIR BREATHING

  • 1 January 1982
    • journal article
    • research article
    • Vol. 97  (APR) , 87-99
Abstract
Western Painted Turtles, C. picta bellii (n = 5), were maintained submerged and apneic for 90 days: days 0-21 in severely hypoxic water (P[partial pressure]O2 = 0-5 mm Hg), days 22-43 in aerated water (PO2 .apprx. 160 mm Hg) and days 44-90 again in hypoxic water. From day 90 onward, the water was aerated and the turtles were allowed access to the air; water and air temperatures were maintained at 3.degree. C. Arterial blood samples were taken periodically and analyzed for PO2, PCO2, pH, [Na+], [K+], [Cl-], [lactate-], [glucose] and hematocrit. Plasma [HCO3-] was calculated for all samples and total plasma Ca was measured on samples from 2 animals. Each exposure to low PO2 water caused progressive lactic acidosis and a transient respiratory acidosis with an accompanying fall in plasma [Cl-] and rise in plasma [K+] and [Ca]. During the intervening period in aerated water, blood pH recovered significantly (from 7.33 to 7.74 in 7 days), due primarily to a fall in PCO2 (from 23.5 to 10.6 mm Hg), while [lactate-] remained unchanged (at .apprx. 50 mM) and [HCO3-] rose slightly. Plasma [K+] promptly returned to nearly normal values. When permitted to breathe on day 90, the 3 surviving turtles rapidly restored pH to normal by pronounced hyperventilation (PCO2 < 5 mm Hg). Metabolic acidosis, disappeared slowly with a t1/2 [half-life] for [lactate-] and [HCO3-] restoration of .apprx. 2 wk. A wintering turtle can stabilize or even slightly improve its acid-base and ionic status by moving from an anoxic environment to well-oxygenated water. Further improvement can be gained by breathing air, but recovery proceeds at a very slow rate if the animal remains at 3.degree. C.

This publication has 1 reference indexed in Scilit: