Zhang X Q, Pang L, Eyzaguirre C
Department of Physiology, University of Utah School of Medicine, Salt Lake City 84108, USA.
Brain Res. 1995 Apr 10;676(2):413-20. doi: 10.1016/0006-8993(95)00158-m.
Carotid bodies of rats and mice were used to measure the intracellular potassium activity, ai(K), of clustered and isolated glomus cells normally oxygenated (pO2 102-139 Torr), and during hypoxia (pO2 2-82 Torr) induced by Na-dithionite. ai(K) was measured with intracellular ion-selective microelectrodes, and the resting potential (EM) with KCl-filled micropipettes. Under normoxia, the ai(K) of clustered cells in both species was higher than that of isolated cells. This resulted in more negative potassium equilibrium potentials (EK's). There was no correlation between ai(K) and EM in clustered cells, but this correlation was significant in isolated cells. Hypoxia significantly decreased ai(K) in clustered and single mouse cells, and in clustered rat cells, although its effects on single rat cells were variable. ai(K) decreases were accompanied by cell depolarization and positive shifts in EK. During hypoxia, there were significant correlations between ai(K) and EM in all cells. It is suggested that ai(K) did not influence the EM of clustered cells under normoxia because of interference by K+ pumping mechanisms toward glomus cells from surrounding sustentacular processes. This hindrance is not present when glomus cells are isolated. During hypoxia K+ pumping from sustentacular cells is disrupted, allowing the EM of clustered glomus cells to follow their ai(K) and behave like isolated cells. The different effects of hypoxia on isolated rat and mouse cells may be due to activation of different types of glomus cells.
采用大鼠和小鼠的颈动脉体来测量正常氧合（pO₂ 102 - 139托）以及连二亚硫酸钠诱导的低氧（pO₂ 2 - 82托）条件下，成团和分离的球细胞的细胞内钾活性ai(K)。使用细胞内离子选择性微电极测量ai(K)，并用充满KCl的微吸管测量静息电位(EM)。在常氧条件下，两种动物成团细胞的ai(K)均高于分离细胞。这导致钾平衡电位（EK）更负。成团细胞的ai(K)与EM之间无相关性，但在分离细胞中这种相关性显著。低氧显著降低了小鼠成团和单个细胞以及大鼠成团细胞中的ai(K)，尽管其对大鼠单个细胞的影响存在差异。ai(K)降低伴随着细胞去极化和EK的正向偏移。在低氧期间，所有细胞的ai(K)与EM之间均存在显著相关性。这表明在常氧条件下，ai(K)不影响成团细胞的EM，因为从周围支持细胞向球细胞的K⁺泵机制产生了干扰。当球细胞分离时不存在这种阻碍。在低氧期间，支持细胞的K⁺泵被破坏，使得成团球细胞的EM能够跟随其ai(K)并表现得像分离细胞一样。低氧对分离的大鼠和小鼠细胞的不同影响可能是由于不同类型球细胞的激活。
