58 Innervation of the Glandular Elements 



vious administration of priscol, without decreasing the secretory 

 sympathetic response. This is shown in Fig. 3.7 in which both 

 secretion and blood flow were recorded. It can be seen that sym- 

 pathetic stimulation, after priscol, neither decreased the blood flow 

 nor the secretion during chorda stimulation. But it did not increase 

 the salivary flow either; the fact that this did not occur in the 

 absence of priscol, therefore, was not due to a sympathetic vaso- 

 constriction. 



Strong evidence for a double innervation of the gland cells was 

 obtained when the nerves were stimulated during intracellular elec- 

 trical recording (Lundberg, 1955). In the microelectrode "type 1" 

 response of submaxillary glands, supposed to originate from alve- 

 olar cells, the resting membrane potential of the cell could be 

 increased both by chorda and sympathetic stimulation. In the 

 "type 2" response, probably from demilune cells, chorda stimu- 

 lation gave hyperpolarization, but sympathetic stimulation depolar- 

 ization. In the sublingual gland of the cat only one type of response 

 was found; both nerves affected the potential, both raising the 

 potential over the outer membrane above the resting level (Lund- 

 berg, 1957). 



Experiments by Stromblad (19576) indicate that the two chemi- 

 cal mediators act on the same cells. The oxygen consumption of 

 chopped submaxillary glands of cats was measured manometrically. 

 Acetylcholine, adrenaline and noradrenaline increased the respira- 

 tion. When one of the drugs was given in a dose causing its maximal 

 effect, another of the drugs could not further increase the response. 



Hokin and Sherwin (1957) found that acetylcholine and adrenal- 

 ine stimulate the secretion of amylase and the incorporation of 32 P 

 into the phospholipids in slices of parotid glands of rabbits. The 

 effects of maximal concentrations of the drugs were not additive, 

 suggesting that the two drugs acted on the same cells of this gland 

 also. 



Section of the chorda tympani is followed by a pronounced super- 

 sensitivity of the gland cells to adrenaline (and acetylcholine). It 

 seems unlikely that cells not normally excitable by adrenaline 

 should become susceptible to this agent through denervation ; for 

 instance, it may be pointed out that the maximal rate of secretion 

 on adrenaline injection is not higher in the denervated than in the 

 normal gland (Emmelin and Muren, 1951). As the sympathetic 

 seems to be able to affect all the cells sensitive to adrenaline, it is 



