202 Theories of Secretion 



changed by no more than i mV (Lundberg, 1957a). However, 

 with continued stimulation, the potential over the inner cell mem- 

 brane also gradually rose by some 10 mV but never attained the 

 same degree of hyperpolarization as that of the outer cell mem- 



Fig. 10.5. At the left of the figure the microelectrode is within a sublingual 

 cell and the hyperpolarization on chorda stimulation is seen. 



The sudden potential jump back to zero is due to the electrode being inserted into the acinar 

 lumen. A very similar hyperpolarization is still recorded (Lundberg, 19570). 



Fig. 10.6. Intracellular recording from a sublingual gland cell with a 

 double-barrelled microelectrode. 



Current was passed through the second barrel to shift the cell resting potential from 8 mV 

 at one extreme to 102 mV at the other. Chorda stimulated at 25 c/s during period indicated by 

 white line (Lundberg, 19576). 



brane (Fig. 10.5). Lundberg (19576, c) has further shown that 

 hyperpolarization of the outer membrane (Fig. 10.6) is practically 

 independent of the resting potential when this is shifted from 8 mV 

 to 102 mV by the passage of current through a second intracellular 

 electrode. This finding is of great importance and immediately 



