Chronically reserpinized rat as a model for cystic fibrosis: Na+ transport inhibitory effect in submaxillary saliva.

The retrograde perfusion assay in the rat parotid gland was used to 
investigate the effects of salivary secretions from control and reserpine-treated rats 
on Na+ reabsorption. Results demonstrated that submaxillary saliva from the treated 
animals caused a 69% inhibition of Na+ reabsorption, accompanied by a 
28% reduction in the volume of saliva secreted, and a 22% 
reduction in flow rate. By contrast, submaxillary saliva from control rats 
caused a 6% inhibition of Na+ reabsorption, a 6% reduction in 
volume, and a 5% reduction in flow rate. Parotid saliva from 
reserpine-treated rats also inhibited Na+ reabsorption to the extent of 39% 
and caused a 38% reduction in volume and a 33% reduction 
in flow. Parotid saliva from control rats only inhibited Na+ reabsorption 
to the extent of 2.7% and caused a 4-- 6% reduction 
in salivary volumes and flow rates. The inhibition of Na+ reabsorption 
and the reduction in salivary volume and flow rates caused by 
submaxillary saliva of reserpine-treated rats were either abolished or significantly reduced 
when the saliva was previously heated to 100 degrees C, frozen, 
and then thawed or kept in glass tubes at 4 degrees 
C for 24 hr. These results indicate that saliva from reserpine-treated 
rats have comparable effects in this assay system to those of 
saliva from cystic fibrosis (CF) patients and further support its use 
as an animal model for this disease. 