The effect of hypoxia on the response of the carotid body chemoreceptor to potassium in the anaesthetized cat.

The effect of hypoxia on the response of the carotid chemoreceptor to potassium has been investigated in anaesthetized cats. After an initial period of ventilation on air, FIO2 was reduced to 0.1-0.13 to give a mean PaO2 of 44 mm Hg. KCl was infused intravenously to raise arterial K+ to approximately 6 mM and hold it at that level. For 8 experiments in 7 cats, mean chemoreceptor discharge increased from 1.9 impulses.sec-1 on air, to 7.3 impulses.sec-1 during hypoxia to a peak of 12.2 impulses.sec-1 after the first 0.25 min of the potassium infusion. The initial speed of response and pattern of adaptation were similar to those seen in normoxic cats, but the combined effects of hypoxia and hyperkalaemia on carotid chemoreceptor discharge were greater than the sum of the individual effects.