Extrarenal ammonia excretion in the terrestrial pulmonate, Otala lactea

[摘要] An extrarenal nitrogen product has been identified in two terrestrial snails, Otala lactea and Helix 2219.0a. The nitrogen waste has been determined qualitatively to be ammonia, This ammonia which is excreted has also been measured quantitatively bat no correlation could be found between the amount of ammonia excreted and the size of the snail, The ammonia excretion was circadian with the majority of the waste being excreted during the daytime, Ammonia was formed by lung tissue homogenates in the absence of added substrates, but this could not be found for blood. Urea and amino acids were added as substrate and urea was the only significant substrate for ammonia production. The levelsof ammonia and urea concentration have been measured in dif-ferent tissues. Urease activity has been found and characterized. It was found to be non-bacterial in origin. An approximation was made of the percentage of total nitrogen excreted extrarenally and found to be 38%. On the basis of this approximation it was thought to be a significant means of nitrogen excretion. A dramatic increase in blood pH was found for Otala lacteal Helix aspersa and Busycon. This was found to be due to the loss of physically dissolved carbon dioxide. Carbonic anhydrase activity was not found in Otala blood but was present in lung and hepatopancreas. The significance of this pH increase as it relates to extrarenal ammonia excretion is discussed.

[发布机构] Rice University