EFFECTS OF HYPOXIA ON THE INTRACELLULAR K+ OF CLUSTERED AND ISOLATED GLOMUS CELLS OF MICE AND RATS

Carotid bodies of rats and mice were used to measure the intracellular potassium activity, a(i)(K), of clustered and isolated glomus cells n ormally oxygenated (pO(2) 102-139 Torr), and during hypoxia (pO(2) 2-8 2 Torr) induced by Na-dithionite. a(i)(K) was measured with intracellu lar ion-selective microelectrodes, and the resting potential (E(M)) wi th KCl-filled micropipettes. Under normoxia, the a(i)(K) of clustered cells in both species was higher than that of isolated cells. This res ulted in more negative potassium equilibrium potentials (E(K)'s). Ther e was no correlation between a(i)(K) and E(M) in clustered cells, but this correlation was significant in isolated cells. Hypoxia significan tly decreased a(i)(K) in clustered and single mouse cells, and in clus tered rat cells, although its effects on single rat cells were variabl e, a(i)(K) decreases were accompanied by cell depolarization and posit ive shifts in E(K). During hypoxia, there were significant correlation s between a(i)(K) and E(M) in all cells. It is suggested that a(i)(K) did not influence the E(M) of clustered cells under normoxia because o f interference by K+ pumping mechanisms toward glomus cells from surro unding sustentacular processes. This hindrance is not present when glo mus cells are isolated. During hypoxia K+ pumping from sustentacular c ells is disrupted, allowing the E(M) of clustered glomus cells to foll ow their a(i)(K) and behave like isolated cells. The different effects of hypoxia on isolated rat and mouse cells may be due to activation o f different types of glomus cells.