[Effect of the macrocyclic polyether 15-crown-5 on the ionic permeability of excitable membranes]

The macrocyclic polyether 15-crown-5 at a concentration of 5 . 10(-5)-10(-3) M reduced the frequency of the contractions of an isolated rat auricle, increasing the refractory period of the contractions. The polyether lowered the rate of activation of the slow input current of rat spinal ganglionic neurons and blocked the sodium channels of the electroexcitable membrane without disturbing the function of activation and inactivation mechanisms. The compound under study considerably delayed the onset of and decelerated reactivation of the sodium input current. These actions were calcium-dependent, becoming more demonstrable with reduction of Ca2+ concentration outside the cell. 15-Crown-5 interfered with the action of Ca2+ on the lipid bilayer membrane potential. It is assumed that all the effects described are determined by the formation of 15-crown-5-Ca2+ complexes, thereby leading to the impairment of the packing of the membrane lipoprotein matrix.