| Autor: |
Huber, Korinna, Roesler, Uta, Muscher, Alexandra, Hansen, Kathrin, Widiyong, Irkham, Pfeffer, Ernst, Breves, Gerhard |
| Předmět: |
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| Zdroj: |
American Journal of Physiology: Regulatory, Integrative & Comparative Physiology; Feb2003, Vol. 53 Issue 2, pR413, 9p, 5 Black and White Photographs, 4 Charts, 10 Graphs |
| Abstrakt: |
The rapid development of precocial goats in the first-weeks after birth requires an adequate adaptation of phosphate transport systems to maintain the P homeostasis at each developmental stage. Here we examined the age-related development of Na[sup +]-P[sub i] transport systems in small intestines, kidneys, and parotid glands of goats. Kinetic parameters were determined by brush-border membrane vesicle uptake studies, and relative expression of NaPi type II mRNA and protein was recorded by molecular biological methods. High intestinal P[sub i] transport capacity was already present on the first day of life. Within the first 3 wk of life there seemed to be a change in the type of Na[sup +]-dependent P[sub i] transporter, and NaPi IIb was expressed increasingly up to the fifth month of life. Renal Na[sup +]-P[sub i] transport capacity was also high at birth, and this was associated with high expression levels of NaPi IIa mRNA, indicating the important role of this transporter for renal P[sub i] reabsorption. At weaning an increase in both intestinal and renal Na[sup +]-P[sub i] transport balanced the increasing requirements for P[sub i] to establish the endogenous P[sub i] cycle. Salivary P[sub i] concentration and parotid NaPi II mRNA rose markedly to guarantee an adequate P[sub i] supply for rumen microbes. We concluded that the high demand for P[sub i] in young goats was assured by high basal Na[sup +]-P[sub i] transport capacity of small intestines and kidney expressed continuously during ontogenesis. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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