PMC:2812702 / 8191-9904 JSONTXT

{"target":"https://pubannotation.org/docs/sourcedb/PMC/sourceid/2812702","sourcedb":"PMC","sourceid":"2812702","source_url":"https://www.ncbi.nlm.nih.gov/pmc/2812702","text":"This led Langley to pursue two lines of research that were also of interest to other physiologists of the time: one was the question whether pharmacological substances act directly on the body tissues or indirectly by affecting the endings of nerves leading into these tissues; the other was the question how antagonistic action between drugs, for example the one Langley had shown between jaborandi and atropine, came about. In a further series of experiments, he demonstrated the antagonism between pilocarpine (an alkaloid of jaborandi) and atropine on salivary secretion in dogs and cats; pilocarpine stimulated secretion, atropine stopped it, a new dose of pilocarpine got it going again, a further dose of atropine stopped it, and so on. How could this be explained? Obviously the relative concentration of the two substances in the animal body played a role, and both substances had to have a chemical affinity to the relevant tissues. In 1878 Langley formulated the following hypothesis:… we may, I think, without much rashness, assume that there is some substance or substances in the nerve endings or gland cells with which atropin and pilocarpin are capable of forming compounds. On this assumption then the atropin or pilocarpin compounds are formed according to some law of which their relative mass and chemical affinity for the substances are factors. In the analogous case with inorganic substances, other things being equal, these are the sole factors. To take the simplest case, if a and b are both able to form, with y, the compounds ay, by, then ay and by are both formed, quantity of ay and by depending on the relative masses of a and b present and their relative chemical affinity to y[14].","tracks":[]}