Burleson Mark L, Mercer Stephen E, Wilk-Blaszczak Malgosia A
Department of Biological Sciences, University of North Texas, Box 305220, Denton, TX, USA.
Brain Res. 2006 May 30;1092(1):100-7. doi: 10.1016/j.brainres.2006.03.085. Epub 2006 May 11.
Little is known about the cells or mechanisms of O2 chemoreception in vertebrates other than mammals. The purpose of this study, therefore, was to identify O2-sensitive chemoreceptors in a fish. Putative O2-sensitive chemoreceptors were dissociated from the gills of channel catfish, Ictalurus punctatus, and cultured. A population of cells was identified with morphology and a histochemical profile similar to mammalian carotid body Type I (glomus) cells and pulmonary neuroepithelial cells. These cells stain with neutral red and appear to be the branchial neuroepithelial cells. Immunocytochemical staining showed that these cells contain neuron-specific enolase (NSE), tyrosine hydroxylase (TH) and 5-hydroxytryptamine (5HT). Patch-clamp experiments showed that these cells have a O2-sensitive, voltage-dependent outward K+ current like mammalian O2 sensors. Two kinds of electrophysiological responses to hypoxia (P(O2) < 10 Torr) were observed. Some cells showed inhibition of outward current in response to hypoxia, whereas other cells showed potentiation. Neurochemical content and electrophysiological responses to hypoxia indicate that these cells are piscine O2-sensitive chemoreceptors.
除哺乳动物外，关于脊椎动物中氧气化学感受的细胞或机制我们知之甚少。因此，本研究的目的是在一种鱼类中鉴定对氧气敏感的化学感受器。从斑点叉尾鮰（Ictalurus punctatus）的鳃中分离出假定的对氧气敏感的化学感受器并进行培养。鉴定出了一群细胞，其形态和组织化学特征与哺乳动物的颈动脉体I型（球）细胞和肺神经上皮细胞相似。这些细胞用中性红染色，似乎是鳃神经上皮细胞。免疫细胞化学染色表明这些细胞含有神经元特异性烯醇化酶（NSE）、酪氨酸羟化酶（TH）和5-羟色胺（5HT）。膜片钳实验表明，这些细胞具有像哺乳动物的氧气感受器一样的对氧气敏感的、电压依赖性外向钾电流。观察到了对缺氧（P(O2) < 10 Torr）的两种电生理反应。一些细胞在缺氧时表现出外向电流的抑制，而其他细胞则表现出增强。神经化学含量和对缺氧的电生理反应表明这些细胞是鱼类对氧气敏感的化学感受器。
