559 Bioelectrochemistry and Bioenergetics, 17 (1987) 559-566 A section of J. Electroanai. Chem., and constituting Vol. 231 (1987) Elsevier Sequoia S.A., Lausanne - Printed in The Netherlands zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQP %2 - THE SIMPLEST POSSIBILITY FOR THE APPEARANCE OF SELF-OSCILLATIONS IN PACEMAKER CELLS N.I. MARKEVICH Institute of Biological Physics of the Academy of Sciences of the USSR, 142292 Pushchino, Moscow Region (U.S.S.R.) K.V. KAZARIAN * L.A. Orbeli Institute of Physiology, Academy of Sciences of the Arm.SSR, 22 Orbeli Brass. Str., 375028, Yereoan (U.S.S.R.) SM. MARTIROSOV Yerevan State University, Department of Biophysics, Mravian Str., 375049, Yerevan (U.S.S.R.) (Revised manuscript received May 4th 1987) SUMMARY This paper considers the simplest case of the appearance of membrane potential self-oscillations, the one which is connected only with the circulation of sodium ions between the cell and the medium. It is shown that the presence of a potential-dependent Na+ channel and a Naf -K+ pump in the membrane is sufficient for the appearance of a wide spectrum of oscillatory processes. INTRODUCTION One of the features of the smooth muscle is its capacity for a spontaneous rhythmical electrogenesis. Two components of the spontaneous electric activity are noted: slow-wave oscillations of the membrane potential value, and rapid activity shown in the form of action potentials. It is supposed that the spontaneous activity is connected in particular with the operation of the Na+-K+ pump [l-4]. The influence of the temperature, metabolic inhibitors, ouabain and potassium-free medium, either on the slow wave (SW) or its certain components, has been demonstrated [1,4-61. It is supposed that the above-mentioned correlation between the Na+-Kt pump and slow-wave rhythmogenesis is possible only under the electrogenicity of the l To whom correspondence should be addressed. 0302-4598/87/$03.50 0 1987 Elsevier Sequoia S.A