The electrical phenomena accompanying the excitation of so-called secretory and trophic nerve fibres, in the salivary glands of the dog and cat / by J. Rose Bradford.

Bradford, John Rose, Sir, 1863-1935.

Date:: [1887?]

Credit: The electrical phenomena accompanying the excitation of so-called secretory and trophic nerve fibres, in the salivary glands of the dog and cat / by J. Rose Bradford. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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$electrical variations. Against the above view it might be urged, that what has been called the first phase, i.e. outer surface of gland negative to hilus, is not vasomotor, owing to the ease with which it is abolished by atropin; but that the second phase, i.e. outer surface of gland positive to hilus, is due to these vasomotor changes. At first sight, there are a certain number of facts, apparently in favour of the view that this second phase is vasomotor. Thus this is the phase that occurs most often on sympathetic excitation in the dog, and this is the phase that is most refractory to atropin, requiring as much as 100 mgrms. sometimes to abolish it. Further in the dog, after 5—10 mgrms. of atropin have abolished the usual chorda variation, i.e. outer surface negative to hilus, a small second phase is seen, and it might be concluded that both here and on sympathetic excitation, this second phase was due to vasomotor effects. But a fact strongly militating against this conclusion, is found in the cat. In this animal this second phase, which is seen both on chorda and sympathetic excitation, is readily abolished by doses of atropin, only slightly larger than those necessary to abolish the chorda first phase in the dog; 20—40 mgrms. of atropin being sufficient in the cat, to completely abolish both first and second phase, in the case both of the chorda and of the sympathetic. Hence if we were to assume that the second phase was due to vaso- motor effects, we should have to suppose that these are more readily abolished by atropin in the cat, than they are in the dog: for which hypothesis there is no proof, whereas it is well known that atropin abolishes the secretion in the cat in smaller doses, than those required to do the same in the dog. In fact it is only in the case of the sympa- thetic of the dog, that it is at all probable, that the electrical phenomena are due to vasomotor changes. However, when we consider that a varia- tion of similar sign is much more readily abolished in the cat than in the dog; that the secretory activity of this nerve in the dog, requires as much as 100 mgrms. of atropin to abolish it, and that this dose also abolishes the electrical phenomena; we can scarcely drawr any other conclusion, than that the electrical phenomena observed are not due to vasomotor changes. We will now proceed to discuss the question, as to whether any of the electrical phenomena are due to phenomena grouped under heads 3 and 4; that is to say, to the chemical or physical changes in the gland cells, that necessarily precede the flow of liquid, or to the flow of liquid itself. There is no doubt that some of the electrical phenomena are closely$