The effect of tetraethylammonium and 4-aminopyridine on mechano- and electrosensitive channels of the Pacinian corpuscle

The action of tetraethylammonium (TEA) (20 mM) and 4-aminopyridine (4-AP) (5 mM) on mechano- and electrically excitable membranes of the Pacinian corpuscles was studied by means of the air gap technique in constantly perfused preparations. Extracellular recordings of receptor potential have shown that application of TEA causes 1.5-fold prolongation of the receptor potential and a decrease of its amplitude by 40%. 4-AP has no effect on the mechanosensitive membrane. The difference in the blockers effect testifies that repolarization of the receptor potential is not regulated by the voltage-dependent potassium channels. The blockers considered are likely effect on the calcium-dependent potassium currents activated by Ca 2+ ions passing through the non-selective channels opening in response to mechanical stimulus. TEA and 4-AP induce a 2- to 3-fold increase of the action potential duration in the electrically excitable membrane of the Ranvier node. Computations based on the Dodge model help reveal that inhibition of the voltage-dependent potassium channels accounts for this increase.