THE SPINY MOUSE (ACOMYS CAHIRINUS),—A RODENT PROTOTYPE FOR STUDYING PLASMA VOLUME REGULATION DURING THERMAL DEHYDRATION

ABSTRACT

During thermal dehydration, extensive mobilization of the evaporative cooling system induces rapid reduction of total body water. The fraction of water contributed to evaporative cooling from each fluid compartment is not equal. Those species which show an ability to conserve their plasma water despite dehydration show better endurance under these stressful conditions. The common spiny mouse (Acomys cahirinus) was a prototype for elucidating the mechanisms underlying plasma volume (PV) conservation. Data accumulated since 1965 on the spiny mouse, as well as on other rodents and larger mammals, suggest that PV conservation during rapid dehydration relies primarily on the ability of the PV conservers to decrease plasma protein extravasation. The mechanisms responsible for this response are coupled to thermally-induced redistribution of cardiac output and to structural changes in the capillary wall. This feature seems to reflect a selective trait for hot, arid environments.