Alkaline secretion by amphibian duodenum. I. General characteristics.
Alkaline secretion by amphibian duodenum. I. General characteristics.
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两栖动物十二指肠的碱性分泌。
DOI：
10.1152/ajpgi.1981.240.5.g401
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
Silen,W
中科院分区：
文献类型：
--
作者：
Simson,JN;Merhav,A;Silen,W
剥去牛蛙近端十二指肠，置于HCO3缓冲营养液（浆膜）和未缓冲分泌液（管腔）溶液之间的Ussing腔中。该制剂具有稳定的电参数，能以0.95 +/- 0.03 μ q.cm-2.h-1（平均+/- SE； n = 100）的速率引起分泌液的碱化。缺氧和2,4-二硝基苯酚均能降低碱化50-60%，但乙酰唑胺（5 × 10(-4)M）没有影响。去除营养物质HCO3-和CO2可使碱化率降低90%以上，而在恒定CO2分压（PCO2）下增加营养物质[HCO3-]或在恒定[HCO3-]下增加营养物质PCO2均可引起碱化率的饱和增加，尽管对营养物质ph有相反的影响。二丁基腺苷3′，5′-环单磷酸，而非二丁基鸟苷3′，5′-环单磷酸，可使管径碱化率提高到对照的167 +/- 21%。去除营养物，但不分泌，Na+减少碱化74%。碱化速率的变化伴随着相应的电位差和短路电流的变化。去除Cl-或营养K+或添加组胺、硫氰酸盐或儿茶酚胺对电或分泌特性没有影响。我们得出结论：a)两栖动物十二指肠通过主动和被动过程将碱从营养液转运到分泌液，b)内源性HCO3-分泌少量，c)碱性分泌是电致的，d) Cl-不参与短路电流，e)碱性分泌部分依赖于营养Na+， Na+起促进作用，而不是共同运输作用，f)没有Cl- HCO3-交换，g)碱性分泌不受营养pH的影响。
Stripped, proximal bullfrog duodenum was mounted in an Ussing chamber between HCO3--buffered nutrient (serosal) and unbuffered secretory (luminal) solutions. This preparation showed stable electrical parameters and caused alkalinization of the secretory solution at a rate of 0.95 +/- 0.03 mueq.cm-2.h-1 (mean +/- SE; n = 100). Anoxia and 2,4-dinitrophenol each reduced alkalinization by 50–60%, but acetazolamide (5 X 10(-4)M) had no effect. Removal of nutrient HCO3- and CO2 reduced alkalinization by over 90%, whereas increasing nutrient [HCO3-] at constant partial pressure of CO2 (PCO2) or increasing nutrient PCO2 at constant [HCO3-] each caused saturable increases in alkalinization, despite opposite effects on nutrient pH. Dibutyryl adenosine 3',5'-cyclic monophosphoric acid, but not dibutyryl guanosine 3',5'-cyclic monophosphoric acid, increased luminal alkalinization to 167 +/- 21% of control. Removal of nutrient, but not secretory, Na+ reduced alkalinization by 74%. Changes in the rate of alkalinization were accompanied by corresponding changes in potential difference and short-circuit current. Removal of Cl- or nutrient K+ or addition of histamine, thiocyanate, or catecholamines had no effect on electrical or secretory characteristics. We conclude that a) the amphibian duodenum transports alkali from nutrient to secretory solutions by both active and passive processes, b) there is a small secretion of endogenous HCO3-, c) alkaline secretion is electrogenic, d) Cl- does not contribute to the short-circuit current, e) alkaline secretion is partially dependent on nutrient Na+ that acts in a facilitatory, not cotransport, role, f) there is no Cl--HCO3- exchange, and g) alkaline secretion is independent of nutrient pH.