Paracellular solute uptake by the freshwater zebra mussel,
dreissena polymorpha.
Dietz, Thomas H., Roger A. Byrne, John W. Lynn, and Harold Silverman.
Department of Zoology and Physiology, Louisiana State University,
Baton Rouge, 70803 and Department of Biology, SUNY College at
Fredonia,14063
APStracts 2:0062R, 1995.
A hyperosmotic solution of mannitol or glucose (100 mM) in pondwater
caused an increase in paracellular solute movement between the
bathing medium and body fluids of D. polymorpha. Small molecules (<
5000 Da) in the bath entered the mussel and 80_85% of the Na and Cl
in the blood was lost within 12 h. Blood total solute was elevated
within 4 h exposure to hyperosmotic conditions, but the rise was
attributed to the gain of glucose or mannitol from the bath, and not
due to an elevation of ion concentration as a result of the osmotic
loss of water. Lanthanum present in the bathing solution was able to
penetrate the paracellular junctional complex between gill epithelial
cells in mussels exposed to hyperosmotic conditions, but was rarely
observed in pondwater acclimated animals. Colloidal gold (6 nm
diameter) was unable to penetrate the paracellular space but was
accumulated in endocytotic vesicles in many epithelial cells. The
$QUOTleakiness$QUOT of the epithelial tissue may be a critical factor
in the low blood solute concentrations in freshwater mussels despite
high rates of ion transport found in these animals.
Received 4 November 1994; accepted in final form 28 February
1995.
APS Manuscript Number R634-4.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 10 March 1995.