On reflex cardiac inhibition

T. G. Brodie, A. E. Russell
1900 Journal of Physiology  
IT has long been known that slowing or arrest of the heart can be brought about reflexly by excitation of almost any afferent nerve of the body if the stimulus be sufficiently great, and that the one nerve wbich can most readily produce this reflex effect is the vagus. The systematic examination of the different branches of the vagus with the direct object in view of determining which fibres play the most important part in producing the reflex has not however been carried out. Hence the
more » ... . Hence the experiments described in this paper have been designed. Our experiments can be conveniently grouped for descriptive purposes in two sections, in the first of which we deal with the results obtained by electrical excitation of the vagal branches and in the second, with other modes of excitation,-chemical, mechanical, etc. -which followed as a direct consequience of the results we obtained in our first series. Most of our experiments have been performed upon dogs, the anaesthetic employed being, as a rule, the A.C.E. mixture. In a few cases urethane was used, which was administered either subcutaneously or by intravenous injection; the dose given was 1-25 grm. per kilo of body weight. The results were precisely the same with both forms of anaesthesia. We have also confirmed our results upon cats and found the reaction the same in this animal as in the dog. To record the effect upon the heart we usually took the carotid blood-pressure curve as being on the whole the most convenient. The records thus obtained were always checked by direct observation of the
doi:10.1113/jphysiol.1900.sp000824 pmid:16992570 fatcat:byjhretstfaovb4t742r5jv5qq