INTESTINAL PHOSPHATE-TRANSPORT IN SPONTANEOUSLY HYPERTENSIVE RATS AND GENETICALLY MATCHED CONTROLS
INTESTINAL PHOSPHATE-TRANSPORT IN SPONTANEOUSLY HYPERTENSIVE RATS AND GENETICALLY MATCHED CONTROLS
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DOI：
10.1016/0016-5085(90)91236-y
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发表时间：
1990-07-01
期刊：
影响因子：
29.4
通讯作者：
SHIBATA, H
中科院分区：
文献类型：
--
作者：
GHISHAN, FK;ARAB, N;SHIBATA, H
Hypophosphatemia has been documented in patients with hypertension and in spontaneously hypertensive rats compared with genetically matched control Wistar-Kyoto rats. However, renal tubular reabsorption is increased in spontaneously hypertensive rats. Therefore, it was hypothesized that decreased serum phosphate levels in spontaneously hypertensive rats may be related to a decrease in the intestinal transport of phosphate. To test this hypothesis, sodium-dependent phosphate uptake by jejunal brush-border membrane vesicles of spontaneously hypertensive rats and genetically matched Wistar-Kyoto rats was determined. Phosphate uptake consisted of two components: sodium-independent passive diffusion across the brush border and sodium-dependent, carrier-mediated uptake. The initial rate of uptake in spontaneously hypertensive and Wister-Kyoto rats was linear up to 20 seconds. The initial rate and time course of jejunal sodium-dependent phosphate uptake was decreased in adult spontaneously hypertensive rats compared with correponding mean values in Wister-Kyoto rats. This decrease was secondary to a decrease in Vmax rather than Km, suggesting that the number and/or the activity of the sodium-phosphate transporters is decreased. Sodium-dependent phosphate uptake was pH dependent, with greater uptake at pH 6.0 than at pH 7.4. However, uptake values were lower in spontaneously hypertensive rats than in Wistar-Kyoto rats at all pH levels tested. In contrast, sodium-dependent phosphate uptake in weanling rats (prehypertensive state) was not significantly different between spontaneously hypertensive and Wistar-Kyoto rats. Vitamin D deficiency in both spontaneously hypertensive and Wistar-Kyoto rats decreased Vmax and Km of sodium-dependent phosphate uptake, whereas 1,25(OH)2 vitamin D3 administration increased Vmax and Km in both spontaneously hypertensive and Wistar-Kyoto rats. These results suggest that the hypophosphatemia seen in adult spontaneously hypertensive rats is secondary to a decrease in sodium-dependent phosphate uptake compared with controls. The sodium-phosphate transporter in spontaneously hypertensive rats is responsive to vitamin D administration.
