INFLUENCE OF INCREASING HEART RATE ON THE ALTERATIONS OF THE CARDIAC VENTRICULAR FIBRE-CELLS ACTION POTENTIALS INDUCED BY THIAMINE DEFICIENCY

¹ Institutes of General Physiology and of Human Physiology of the University of Pavia (Pavia), Italy

In rats, the action potentials of myocardial fibre-cells in avitaminosis B₁, induced by a deficient diet or by pyrithiamine administration, were measured by fluctuating microelectrodes on hearts in situ at spontaneous and at externally increased heart rate. The increasing of the heart rate enhanced the modifications of the action potentials of spontaneously beating thiamine-deficient hearts. This suggests that the increased rate may determine a reduction in ion gradients on both sides of the cell membrane.

The slowed spontaneous heart rate of thiamine-deficient rats seems to allow full recovery of the membrane ionic distribution, even if the underlying ion processes were greatly reduced.

Note:

The authors wish to thank Professor C. Casella for invaluable advice and criticism of the manuscript.