Acid-base status of a pulmonate land snail (Helix aspersa) and a prosobranch amphibious snail (Pomacea bridgesi) during dormancy.
Changes in metabolism and acid-base status were compared during dormancy in the pulmonate land snail Helix aspersa and a prosobranch amphibious snail Pomacea bridgesi. The typical condition of higher blood PCO2 and bicarbonate levels for air-breathing versus water-breathing vertebrates was shown for the two snail species. When exposed to dry air for 24 hr, both species depressed oxygen uptake by about 65%. In Pomacea, hypercapnia (increase in hemolymph PCO2 from 5.5 to 18 torr) resulting from dormancy produced no significant change in pH due to large increases in bicarbonate (over 17 mmol/l). In Helix, on the other hand, hypercapnia (increase in hemolymph PCO2 from 13 to 18 torr) resulting from dormancy produced a significant decrease in pH and a less than 7 mmol/l increase in bicarbonate. Pre-existing high levels of bicarbonate in Helix may prevent compensation of hypercapnia resulting from dormancy, similar to the case described for air-breathing vertebrates. Complete compensation of respiratory acidosis during the first 24 hr of dormancy in Pomacea suggests that metabolic rate suppression is independent of pH.
Scholnick
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University of Colorado, Department E.P.O. Biology, Boulder 80309.
Snyder
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GK
Spell
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D000136:Acid-Base Equilibrium; D000222:Adaptation, Physiological; D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D006372:Helix, Snails / Q000378:metabolism*; D006458:Hemolymph / Q000378:metabolism; D009994:Osmolar Concentration; D010101:Oxygen Consumption; D010313:Partial Pressure; D012908:Snails / Q000378:metabolism*
D002245:Carbon Dioxide