Date of Award


Document Type


Degree Name

Master of Science




The marsh clam, Rangia cuneata has been shown in other laboratories to maintain body fluid osmolality above that of the medium in salinities below 10 o/oo. Since the membrane-bound enzyme Na++K+-ATPase has been implicated in the osmoregulatory processes in many aquatic organisms, the levels of Na++K+-ATPase and 3H-ouabain binding in homogenized tissue samples from mantle, gill, rectum, ventricle, kidney, and foot (including epithelial and muscle tissue were measured). Mantle, kidney, and gill contained substantial concentrations of Na++K+-ATPase and 3H-ouabain binding sites. Mantle contained nearly twice the Na++K+-ATPase activity of kidney and more than three that of gill. Mantle also contained the highest number of binding sites. Turnover numbers calculated for each tissue indicated that mantle pump sties have higher catalytic activity than gill or kidney.

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