抄録
1. Changes in the threshold of the Pacinian corpuscle for mech anical stimulation by perfusion with Na-free solution, Li solution and solutions of varying K and Ca concentrations respectively were measured.
2. After perfusion of the corpuscle with Na-free solution the threshold in-creased first and the initiation of impulses was abolished withi n 8 min after perfusion. The impulse reappeared immediately after replacing Na -free solution by the normal one, the threshold returning to the initial value within 3.6 min. 3. Li solution caused an increase in the threshold and abolished the impulse within 22 min after the onset of perfusion, the recovery time being about 30 min, while nerve fibers supplying corpuscles lost their excitability after 90min in Li solution.
4. Perfusion with solutions of low K content and K-free solution produced a slight increase in the threshold, while with 11.2 mM KC1-solution the threshold was decreased. Perfusion with 28.4 mM KCl-solution caused a marked increase in the threshold and abolished the impulse
5. By perfusion with low Ca solution a threshold decrease was obse rved and with Ca-free solution the impulse initiation was maintained for 1 hr, while Ca-free solution containing EDTA blocked the impulse. Effects of EDTA were reversible. With increasing Ca concentration in the perf using solution the threshold increased and in 108 mM Ca-solution the impulse initiation was abol-ished.
6. It is concluded that Na and Li ions are mainly responsible for the gener-ation of the receptor potential but Ca and K ions may not affect the receptor potential directly.
