Electrophysiology of the Glands i gg 



also changed during repeated periods of stimulation. In the cat 

 submaxillary gland with chorda stimulation, the complex com- 

 mences with a hilus positive potential after a latency of 0-2-0-6 

 seconds ; with sympathetic stimulation the latency is a little longer 

 but the initial deflection is also hilus positive. On the other hand, 

 in the sublingual gland, the initial potential is hilus negative with 

 both sympathetic and parasympathetic stimulation and the form 

 of the complex is simpler than in the submaxillary gland. Despite 

 valiant attempts, analysis of the external salivary electrogram has 

 not yielded results useful in explaining secretory activity but the 

 presence of such electrical activity has encouraged the develop- 

 ment of more sensitive methods of study. Lundberg (1955) ex- 

 plored the cat submaxillary gland with intracellular microelec- 

 trodes and was able to distinguish with them three types of 

 potentials generated within cells. 



The first and commonest type (Type I) was obtained from cells 

 near the surface of the gland, some of which could be seen under 

 direct vision to be acinar cells. The resting potential across the 



Fig. 10.3. Intracellular potentials in the cat submaxillary gland obtained from 

 acinar cells (Type I potentials), (a) Potential jump on inserting electrode in the 

 cell and the response to single shocks applied to the chorda, (b) The same type 

 of cell as in (a). 



During the period marked by a white line at the upper margin of the figure, the cervical sym- 

 pathetic was stimulated at 25 c/s: during the period marked by a white line at the lower margin 

 the chorda was stimulated at 25 c/s (Lundberg, 1055)- 



