Norris B C, Pantoja C, Concha J B, Chiang L C
Pharmacology. 1986;33(3):157-66. doi: 10.1159/000138213.
The effects of two bovine heart atrial fractions (AF I and AF II) were investigated in toad skin. When added to the inner (serosal) solution, AF I caused a maximal reversible depression of the transepithelial potential and short-circuit current of about 60% and AF II induced maximal decline of these parameters of only 35%. When added to the outer (mucosal) solution, the effect of both fractions was often only partially reversible. Isaacson's amiloride test showed that AF I decreased the numerical estimates of all the components in the electrical equivalent circuit. The net Na+ flux decreased due to a fall in Na+ flux in the active direction. Incubation with Ca2+-free Ringer's solution decreased and Ca2+ ionophore A 23187 increased the effect of AF II. Partial replacement of sodium by choline in the outer solution slightly reduced the effect and substitution of normal Ringer's solution with sulfate or isethionate Ringer's solution in the outer solution significantly enhanced the effect of the AF. These results indicate that bovine heart atrial natriuretic fractions decrease the sodium potential (ENa), sodium conductance (GNa) and passive conductance (Gsh). The fall in net Na+ transport measured with sodium tracer fluxes confirms the decrease in ENa and GNa.
研究了两种牛心房提取物（AF I和AF II）对蟾蜍皮肤的作用。当将AF I添加到内侧（浆膜侧）溶液中时，它会引起跨上皮电位和短路电流最大程度的可逆性降低，降低幅度约为60%，而AF II仅使这些参数最大下降35%。当将两种提取物添加到外侧（黏膜侧）溶液中时，其作用通常仅部分可逆。艾萨克森的氨氯地平试验表明，AF I降低了等效电路中所有成分的数值估计。由于正向主动转运的Na⁺通量下降，净Na⁺通量降低。用无Ca²⁺的林格氏液孵育会降低AF II的作用，而Ca²⁺离子载体A 23187会增强AF II的作用。外侧溶液中用胆碱部分替代钠会略微降低其作用，而外侧溶液中用硫酸盐林格氏液或羟乙磺酸盐林格氏液替代正常林格氏液会显著增强AF的作用。这些结果表明，牛心房利钠提取物会降低钠电位（ENa）、钠电导（GNa）和被动电导（Gsh）。用钠示踪通量测量的净Na⁺转运下降证实了ENa和GNa的降低。
