Measurements of potassium changes in the cat carotid body under hypoxia and hypercapnia.

With the aid of potassium-sensitive microclectrodes reinforced by bitumen (tip diameter, 1.5 μm), extracellular potassium activity ([K]) and DC potential were measured in the cat's carotid body. Under normoxic and normocapnic conditions, potassium values of 1-16 mM (mean value 7.2 mM, standard deviation 3.8 mM) and DC potential values of −11 mV to +13 mV were recorded. With hypoxia, [K] increased by between 1 mM and 9 mM; DC potential was reduced by between 0.5 and 3 mV. With hypercapnia, [K] decreased by between 1 mM and 5 mM: changes in DC potential were variable. The results suggest that, during hypoxia, potassium influences the nervous structures in the carotid body whereas this influence is absent during hypercapnia. [ABSTRACT FROM AUTHOR]