THE EFFECT OF HYPOXIA ON PLASMA POTASSIUM CONCENTRATION AND THE EXCITATION OF ARTERIAL CHEMORECEPTORS IN THE CAT

Intra‐arterial recordings of potassium concentration ([K + ] a ) and arterial chemoreceptor discharge were made in six anaesthetized cats while tracheal P O2 was stepped every 2 min (end‐tidal P O2 ca . 140, 60, 40 and 95 Torr) at constant PCO2 (33 Torr). [K+]a increased hyperbolically from 3·0 mM to 4·5 mM as arterial P O2 was lowered from 95 to 40 Torr. Because the discharge of arterial chemoreceptors is excited by hyperkalaemia as well as hypoxia, the hypoxic discharge of arterial chemoreceptors may have a component mediated by [K + ] a . The mechanisms underlying the arterial K + increase in hypoxia remain unknown.