Chou C L, Sham J S, Schofield B, Shirahata M
Department of Environmental Health Sciences, School of Hygiene and Public Health, The Johns Hopkins University, Baltimore, MD 21205, USA.
Brain Res. 1998 Apr 13;789(2):229-38. doi: 10.1016/s0006-8993(97)01472-8.
We have recently shown two types of cat carotid body cells based on the oxygen sensitivity of voltage-gated potassium channels. In the present study, we attempted to determine the correlation between cell types (glomus cells, sheath cells, and subtypes of glomus cells) and oxygen sensitivity of potassium channels. Further, changes in membrane potentials in response to hypoxia were also examined. Carotid body cells harvested from adult cats were cultured, and a whole cell patch clamp method was applied to determine the oxygen sensitivity of outward current. The tested cells were identified by Lucifer Yellow in the patch pipette. Glomus cells and sheath cells were immunocytochemically identified using tyrosine hydroxylase (TH) and glial fibrillary acidic protein (GFAP) as markers. The cells whose outward current was inhibited by hypoxia showed TH-immunoreactivity but not GFAP-immunoreactivity. The cells whose outward current was not sensitive to hypoxia were GFAP-positive or TH-negative. One TH-positive cell had oxygen-insensitive outward current. The resting membrane potentials of the cells having oxygen-sensitive outward current were significantly higher (-55+/-3 mV) than those of the cells having oxygen-insensitive outward current (-35+/-2 mV). The former type of cells was depolarized during hypoxia, but not the latter type of cells. These results suggest that most glomus cells of the adult cat carotid body possess oxygen-sensitive potassium channels and are depolarized in response to hypoxia. On the other hand, sheath cells and possibly a small fraction of glomus cells possess oxygen-insensitive potassium channels and their membrane potential is not affected by hypoxia.
最近，我们基于电压门控钾通道的氧敏感性展示了猫颈动脉体的两种细胞类型。在本研究中，我们试图确定细胞类型（球细胞、鞘细胞以及球细胞亚型）与钾通道氧敏感性之间的相关性。此外，还检测了缺氧时膜电位的变化。从成年猫获取的颈动脉体细胞进行培养，并采用全细胞膜片钳方法来测定外向电流的氧敏感性。通过膜片电极中的荧光黄来识别受试细胞。利用酪氨酸羟化酶（TH）和胶质纤维酸性蛋白（GFAP）作为标志物，通过免疫细胞化学方法识别球细胞和鞘细胞。外向电流受缺氧抑制的细胞呈TH免疫反应性，但不呈GFAP免疫反应性。外向电流对缺氧不敏感的细胞为GFAP阳性或TH阴性。一个TH阳性细胞具有对氧不敏感的外向电流。具有氧敏感外向电流的细胞的静息膜电位（-55±3 mV）显著高于具有氧不敏感外向电流的细胞（-35±2 mV）。前一种类型的细胞在缺氧时发生去极化，而后一种类型的细胞则不然。这些结果表明，成年猫颈动脉体的大多数球细胞具有氧敏感钾通道，并在缺氧时发生去极化。另一方面，鞘细胞以及可能一小部分球细胞具有对氧不敏感的钾通道，其膜电位不受缺氧影响。
