Saldeña T A, Saraví F D, Cincunegui L M, Carra Graciela E
Cátedra de Fisica Biológica, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, República Argentina.
Acta Gastroenterol Latinoam. 1997;27(1):19-25.
BACKGROUND/AIM: Short-circuit current (Isc) and transepithelial potential difference (PD) of rat distal colon decrease during acute hypoxia and overshoot on reoxygenation. It is not known whether tonic intrinsic nervous activity may influence these responses.
Preparations lacking the submucosal plexus (islet mucosa) and preparations retaining it (mucosa-submucosa) were mounted in Ussing chambers at 37 degrees C and gassed with 95% O2-5% CO2; Isc and PD were monitored. A 5-min hypoxia with 95% N2-5% CO2 was followed by reoxygenation. The procedure was repeated in the presence of the nervous blocking agent, tetrodotoxin (10(-6)M) in the serosal side of the chamber.
In the isolated mucosa (n = 10) hypoxia reduced Isc by -55 +/- 5% and PD by -54 +/- 6% below baseline; reoxygenatory overshoots were, respectively, +60 +/- 17% and +/- 16%. Tetrodotoxin slightly and transiently reduced baseline Isc (-16 +/- 2%) and PD (-14 +/- 3%), with a small resistivity increase. It did not significatively modify the responses to responses to either hypoxia or reoxygenation. In mucosa-submucosa preparations (n = 9) hypoxia reduced Isc (-54 +/- 8%) and PD (-61 +/- 4%). On reoxygenation Isc and PD were increased, respectively, +30 +/- 5% and +19 +/- 6% over baseline. Tetrodotoxin reduced baseline Isc (-59.6 +/- 5%) and PD (61.3 +/- 6%). It enhanced hypoxic Isc and PD decreases (-80 +/- 5%), but not the reoxygenatory overshoots.
背景/目的：大鼠远端结肠的短路电流（Isc）和跨上皮电位差（PD）在急性缺氧期间降低，复氧时出现过冲。尚不清楚紧张性内在神经活动是否会影响这些反应。
将缺乏黏膜下神经丛的标本（胰岛黏膜）和保留该神经丛的标本（黏膜-黏膜下组织）置于37℃的Ussing小室中，用95%O₂-5%CO₂通气；监测Isc和PD。用95%N₂-5%CO₂进行5分钟缺氧，随后复氧。在小室浆膜侧存在神经阻断剂河豚毒素（10⁻⁶M）的情况下重复该过程。
在分离的黏膜（n = 10）中，缺氧使Isc比基线降低-55±5%，PD降低-54±6%；复氧过冲分别为+60±17%和±16%。河豚毒素轻微且短暂地降低了基线Isc（-16±2%）和PD（-14±3%），电阻略有增加。它对缺氧或复氧反应没有显著影响。在黏膜-黏膜下组织标本（n = 9）中，缺氧使Isc降低（-54±8%），PD降低（-61±4%）。复氧时，Isc和PD分别比基线增加+30±5%和+19±6%。河豚毒素降低了基线Isc（-59.6±5%）和PD（61.3±6%）。它增强了缺氧时Isc和PD的降低（-80±5%），但没有增强复氧过冲。
1）河豚毒素对有黏膜下神经丛支配的标本的基线Isc和PD的影响比对分离黏膜的影响更强烈。2）上皮对急性缺氧的电反应似乎受紧张性神经活动调节。
