Sensory Evoked Responses Recorded Simultaneously from Human Cortex and Scalp

more investigation before its mechanism can be suggested. It is interesting to note that the human colon also shows this variability of response to histamine4 •8 • The effects of bradykinin on human intestinal muscle may be of important patho-physiologieal significance, but there does not appear to be a report of any other direct investigation. Pierce and Webster17 isolated two peptides, kallidin-9 and kallidin-10, from human plasma when it had been activated by urinary kallikrein. Kallidin-9 appeared to be identical with bradykinin and later it was shown that plasma contained an aminopeptidase capable of converting kallidin-10 to kallidin-9 (ref. 18). The precursor of these powerful kinins therefore is present in human plasma and can be converted to bradykinin under experimental condition,;, and there is some evidence that bradykinin may be involved in the inflammatory response19 , 20 • It must, be admitted that the mechanism of intestinal dysfunction in the inflammatory diseases of the bowel is quite unknown. If the bowel wall is as sensitive in vivo as it is under the experimental conditions described in this report, then there is a possibility that increased intestinal movements and spasm could be caused by very small amounts of bradykinin. A much more detailed study of the effects of bradykinin on the human bowel is required and the discovery of a specific antagonist would be of great use. I thank Mr. Alan Parks, consultant surgeon at the London Hospital, for his encouragement and for the facilities to carry out this work in his department. I also thank Miss J. V. Dewell for her technical assistance. This investigation was made possible by a grant from the Medical Research Council.