| Popis: |
SINCE 1933 the transmission of impulses across synaptic or neuromuscular junctions (henceforth called junctional transmission) has been the occasion of a controversy1. The electrical hypothesis has had the grave defect that (except for the falsified isochronism theory) it has never been stated in such precise terms that it could be subjected to crucial tests1,2,3,4,5,6. On the other hand, the chemical hypothesis in its original form (acetylcholine as transmitter) was falsified by an investigation of the action of eserine, and has had to be modified by the addition of ad hoc hypotheses7; but the situation remains unsatisfactory because there seems little hope of testing these ad hoc hypotheses independently, and because recent work suggests that chemical transmission plays a subordinate or negligible part in junctional transmission in sympathetic ganglia3 and the spinal cord4. Meanwhile, during the last eight years important advances have been made in the investigation of the electrical properties of nerve fibres, and of the electrical events occurring in junctional transmission; hence the time has seemed opportune to elaborate on these bases an electrical hypothesis (or model) of transmission that is capable of experimental test. |
