70 JoRN Hess Thaysen 



gland is activated by stimulation of the chorda. A similar 

 internal duct negativity could not be demonstrated in the 

 sublingual gland (Lundberg, 1957a), which (like the lachrymal 

 and pancreatic glands) produces a secretion that is isotonic 

 with the plasma and has a sodium concentration of about 150 

 m-equiv./l. Provided that the potential changes on stimu- 

 lation can be regarded as the electrical signal of ionic trans- 

 port, Lundberg (1957a) concludes that there is a net transport 

 of cation from the lumen to the blood side in the ducts of the 

 submaxillary gland, but not in the sublingual gland. Although 

 the composition of the submaxillary secretion was not 

 measured simultaneously with the duct potential, the latter 

 appears large enough for it be to accepted that the reabsorp- 

 tion of anion is merely a passive sequence of active cation 

 transport. 



With one microelectrode inserted into acinous cells and the 

 other electrode on the gland surface, Lundberg (1955, 1957a) 

 detected a considerable increase in the negativity of the 

 acinous cells on stimulation of the submaxillary as well as of 

 the sublingual gland. The lumen of the acini, likewise, 

 becomes negative as compared to the morphological interior, 

 but this negativity decreases slightly with continued stimu- 

 lation of the gland. These potential changes may be due to a 

 net transport of anion from the blood side into the glandular 

 lumen. In another paper Lundberg (1957c) directly demons- 

 trated this anionic dependence of secretion and secretory 

 potentials in the perfused sublingual gland. Substitution of 

 sodium chloride with sodium nitrate or sodium thiocyanate 

 caused the secretion to stop almost entirely and decreased 

 the potential changes. The secretory response and the 

 potentials reverted to normal when sodium chloride was 

 again added to the perfusate. 



On the basis of the experiments quoted in the present 

 report, it appears reasonable to suggest the following mechan- 

 ism for the secretion of electrolytes and water by the duct- 

 possessing glands. Active outward transport of anions is a 

 main factor in the formation of the secretory products of all 



