Loghman-Adham M, Szczepanska-Konkel M, Yusufi A N, Van Scoy M, Dousa T P
Am J Physiol. 1987 Feb;252(2 Pt 1):G244-9. doi: 10.1152/ajpgi.1987.252.2.G244.
We examined the effect of phosphonoformic acid (PFA) and phosphonoacetic acid (PAA) upon Na+-Pi cotransport in brush-border membrane (BBM) from small gut of rat. Both PFA and PAA inhibited the Na+ gradient-dependent uptake of 32Pi by BBM vesicles (BBMV) prepared from intestinal mucosa but had no effect on Na+-dependent uptakes of D-[3H]glucose, L-[3H]proline, or [14C]succinate. The uptake in the absence of Na+ gradient, or uptake at equilibrium period (180 min), was not affected by PFA or by PAA. A chemical analogue of PFA and PAA, phosphonopropionic acid, had only a minor inhibitory effect and phenylphosphonic acid was inactive. Neither PFA nor PAA influenced the activity of rat intestinal BBM alkaline phosphatase. The BBMV from rat jejunum had a much higher capacity for Na+ gradient-dependent uptake of 32Pi than BBMV from duodenum or ileum. The inhibition of BBMV 32Pi transport across rat jejunum by PFA is competitive. We suggest that PFA and PAA are specific inhibitors of Na+ gradient-dependent uptake of Pi by BBMV from small intestinal mucosa and that they could serve as useful experimental tools for the studies of intestinal Na+-Pi cotransport.
我们研究了膦甲酸（PFA）和膦乙酸（PAA）对大鼠小肠刷状缘膜（BBM）中Na⁺-磷酸共转运的影响。PFA和PAA均抑制了由肠黏膜制备的BBM囊泡（BBMV）对³²Pi的Na⁺梯度依赖性摄取，但对D-[³H]葡萄糖、L-[³H]脯氨酸或[¹⁴C]琥珀酸的Na⁺依赖性摄取没有影响。在不存在Na⁺梯度时的摄取，或在平衡期（180分钟）的摄取，不受PFA或PAA的影响。PFA和PAA的化学类似物膦丙酸只有轻微的抑制作用，而苯膦酸则无活性。PFA和PAA均不影响大鼠肠BBM碱性磷酸酶的活性。来自大鼠空肠的BBMV对³²Pi的Na⁺梯度依赖性摄取能力比来自十二指肠或回肠的BBMV高得多。PFA对大鼠空肠BBMV³²Pi转运的抑制是竞争性的。我们认为PFA和PAA是小肠黏膜BBMV对Pi的Na⁺梯度依赖性摄取的特异性抑制剂，它们可作为研究肠Na⁺-Pi共转运的有用实验工具。
