The effect of Mg2+ and Ca2+ on the excitability of Pacinian corpuscles.

The effect of altering extracellular Ca2+ and Mg2+ levels on electrical properties of Pacinian corpuscles of adult cat has been examined. High Mg2+ solution (5--15 mM) increased the excitability of the receptors and the amplitude of the receptor potential. Ca2+-free EDTA solution caused an increase in the amplitude of the receptor potential in the first 60 min and then its decrease. Mg2+ ions slow down or prevent the depressant effect of the Ca2+ lack on the receptor potential. The phase of the receptor potential amplitude increase in Ca2+-free media was reversibly blocked by tetraethylammonium ions. Treatment with 2,4-dinitrophenol produced a transient increase in the receptor potential amplitude. The threshold of the mechanosensitive receptor membrane was unaffected in Ca2+-free or Mg2+-rich solution. The results suggest that divalent cations are not directly involved in the process of mechanoelectric transformation in Pacinian corpuscles.