THE EFFECT OF NEUROHYPOPHYSEAL HORMONES ON THE PERMEABILITY OF THE TOAD BLADDER TO UREA
THE EFFECT OF NEUROHYPOPHYSEAL HORMONES ON THE PERMEABILITY OF THE TOAD BLADDER TO UREA
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DOI：
10.1172/jci104078
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发表时间：
1960-01-01
影响因子：
15.9
通讯作者：
LEAF, A
中科院分区：
文献类型：
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作者：
MAFFLY, RH;HAYS, RM;LEAF, A
添加到浆膜沐浴介质中的哺乳动物神经垂体激素使渗透系数从26[正负]2.5 （SE） × 10-7 cm/sec增加。至274[正负]3.8 （SE） × 10-7厘米/秒。用c14和n15 -尿素同时测定膜上两个方向的透性，发现在存在和不存在激素的情况下，透性相等。这表明尿素被动地通过膀胱。当尿素浓度达到50毫摩尔时，对尿素的渗透性没有自我抑制的迹象。虽然这表明不存在通过组织的载体介导的运输，但如果尿素与“载体”氢键结合，则不排除这种运输的可能性。虽然激素对尿素渗透性的作用是一个被动的过程，但其作用是高度特异性的。这可以通过激素对膀胱对硫脲的渗透性没有影响来说明。在激素作用后，膜对尿素的渗透性增加，如果不是全部，很大程度上可以由激素增加膜粘膜表面扩散屏障的渗透性的作用来解释。
Mammalian neurohypophyseal hormone added to the serosal bathing medium increases the permeability coefficient from 26[plus or minus] 2.5 (SE) x 10-7 cm/sec. to 274[plus or minus] 3.8 (SE) x 10-7 cm/sec. The permeabilities measured simultaneously in the two directions across the membrane with C14-and N15-urea, respectively, were found equal both in the presence and absence of hormone. This indicates that urea moves passively through the bladder. No evidence of self-depression of the permeability to urea was detected with concentrations of urea in the medium up to 50 mmoles. Although this suggests that there is no carrier-mediated transport through the tissue, it would no exclude the possibility of such transport if urea were hydrogen-bonded to the "carrier". Although the hormonal action on urea permeability effects a passive process, its action, nevertheless, is highly specific. This is illustrated by the absence of an effect of the hormone on the permeability of the bladder to thiourea. The increase in permeability of the membrane to urea following hormone can be largely, if not entirely, accounted for by an action of the hormone to increase the permeability of a diffusion barrier at the mucosal surface of the membrane.