β Scribed by Barnhart, M. Christopher
No coin nor oath required. For personal study only.
Evidence is presented for a role of CO~2~ in acidβbase regulation by airβbreathing gastropods. In the land snail Otala lactea, alterations of PCO~2~ account for pH adjustment during acute temperature change and in compensation for metabolic acidosis. CO~2~ release from the gastropod lung appears to be more closely coupled with ventilation than is O~2~ uptake, because O~2~ uptake is limited to a greater extent by diffusion through the lung epithelium. Cutaneous CO~2~ release may account for half of CO~2~ release from active snails, and the loss of this route during withdrawal into the shell partly accounts for elevation of CO~2~ during dormancy. Further CO~2~ accumulation and consequent acidosis during dormancy is attributable to hypoventilation of the lung. Although respiratory acidosis appears to be involved in metabolic depression during dormancy, the mechanism of influence on cellular metabolism is unknown and is probably indirect. Unlike the respiration of whole animals, respiration of isolated tissues of Otala is insensitive to PCO~2~. Β© 1992 WileyβLiss, Inc.
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