Raddatz E, Katz U, Kucera P
Institute of Physiology, Faculty of Medicine, University of Lausanne, Switzerland.
Am J Physiol. 1991 May;260(5 Pt 1):C1117-24. doi: 10.1152/ajpcell.1991.260.5.C1117.
Oxidative metabolism of isolated toad skin epithelium (Bufo viridis) was investigated in vitro under open-circuit conditions using the spectrophotometric oxyhemoglobin micromethod. This highly sensitive technique has been adapted for studying several epithelia in parallel and for detecting possible regional variations of oxygen uptake in individual epithelium. Changes in the proportion of mitochondria-rich cells (MRC) by ionic acclimation affected oxidative metabolism under nontransporting condition. After acclimation of animals to either NaNO3 or NaCl solutions (100 mmol/l, for greater than 2 wk), the number of MRC per square millimeter in epithelia from nonacclimated and NaNO3- and NaCl-acclimated animals was 350 +/- 113, 460 +/- 196, and 107 +/- 52, respectively. O2 uptake of nonacclimated and NaNO3-acclimated epithelia was significantly higher than that of NaCl-acclimated epithelia (i.e., 0.89 and 0.90 vs. 0.57 nmol O2.h-1.mm-2, respectively). The correlation established between O2 uptake and number of MRC allowed evaluation of the respiration rate of one single MRC, i.e., approximately 1 pmol O2/h. The lowest mitochondrial oxidative activity was found in the epithelia from NaCl-acclimated toads where the uncoupler 2,4-dinitrophenol (50 mumols/l) had the highest relative stimulatory effect (+114%). Acetazolamide (50 mumols/l), a potent inhibitor of carbonic anhydrase mainly present in the MRC, reduced selectively by 31% O2 uptake of the MRC-rich epithelia (NaNO3 acclimated). O2 uptake increased significantly by approximately 80% when basolateral pH increased from 5.8 to 7.8, but did not depend on apical pH. These findings indicate that under nontransporting (open-circuit) conditions, aerobic metabolism of the isolated toad skin epithelium is related to the density and/or characteristics of the MRC.(ABSTRACT TRUNCATED AT 250 WORDS)
采用分光光度法氧合血红蛋白微量法，在开路条件下对离体蟾蜍皮肤上皮（绿蟾蜍）的氧化代谢进行了体外研究。这种高度灵敏的技术已被用于同时研究几种上皮组织，并检测单个上皮组织中氧摄取的可能区域差异。离子适应引起的富含线粒体细胞（MRC）比例的变化会影响非转运条件下的氧化代谢。在将动物分别适应NaNO₃或NaCl溶液（100 mmol/l，超过2周）后，未适应、NaNO₃适应和NaCl适应动物上皮组织中每平方毫米的MRC数量分别为350±113、460±196和107±52。未适应和NaNO₃适应上皮组织的氧摄取显著高于NaCl适应上皮组织（即分别为0.89和0.90对0.57 nmol O₂·h⁻¹·mm⁻²）。氧摄取与MRC数量之间建立的相关性使得能够评估单个MRC的呼吸速率，即约1 pmol O₂/h。在NaCl适应蟾蜍的上皮组织中发现线粒体氧化活性最低，其中解偶联剂2,4-二硝基苯酚（50 μmol/l）具有最高的相对刺激作用（+114%）。乙酰唑胺（50 μmol/l）是一种主要存在于MRC中的碳酸酐酶的有效抑制剂，可选择性地使富含MRC的上皮组织（NaNO₃适应）的氧摄取降低31%。当基底外侧pH从5.8增加到7.8时，氧摄取显著增加约80%，但不依赖于顶端pH。这些发现表明，在非转运（开路）条件下，离体蟾蜍皮肤上皮的有氧代谢与MRC的密度和/或特性有关。（摘要截短于250字）
