Patch-clamp studies on the membrane properties of granulocytes and their changes during cell-activation.

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The blood obtained from the atria of the newts (Triturus pyrrhogaster) contains several types of leukocytes. Under a phase contrast microscope, three types of granulocytes could be identified. Using patch-electrodes, it was possible to investigate the whole-cell membrane currents in these cells. In the neutrophils (diameter, 19-23 mum), identified by characteristic features of lobulated nucleus, inward rectifying K^+ currents were evoked with hyperpolarization from the holding potential of -83 mV. In the presence of Cs^+ (1 mM) or Ba^<2+> (1 mM) in the external saline, the amplitudes of inward currents were reduced with time- and voltage- dependent manner. When the external concentration of K^+ was increased from 4 mM through 20 mM to 100 mM replacing isomolar choline in the perfusing salines, the threshold of the K^+ currents shifted from -83 mV through -43 mV to -3 mV.The amplitude of the evoked K^+ currents also increased as the chord conductance in each of these salines was nearly proportional to the square root of the external K^+ concentration.In basophils and eosinophils, there evoked no major membrane currents under voltage-clamp conditions. Their I-V relations were almost linear, which suggested almost electrically non-excitable properties in these cells. These electrophysiological properties of granulocytes were compared with those of endocrine cells.