Publication: Prolactin directly enhanced Na<sup>+</sup>/K<sup>+</sup>- and Ca<sup>2+</sup>-ATPase activities in the duodenum of female rats
Issued Date
2006-09-14
Resource Type
ISSN
00084212
DOI
Other identifier(s)
2-s2.0-33748463227
Rights
Mahidol University
Rights Holder(s)
SCOPUS
Bibliographic Citation
Canadian Journal of Physiology and Pharmacology. Vol.84, No.5 (2006), 555-563
Suggested Citation
Narattaphol Charoenphandhu, Liangchai Limlomwongse, Nateetip Krishnamra Prolactin directly enhanced Na<sup>+</sup>/K<sup>+</sup>- and Ca<sup>2+</sup>-ATPase activities in the duodenum of female rats. Canadian Journal of Physiology and Pharmacology. Vol.84, No.5 (2006), 555-563. doi:10.1139/Y05-161 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/22980
Research Projects
Organizational Units
Authors
Journal Issue
Thesis
Title
Prolactin directly enhanced Na<sup>+</sup>/K<sup>+</sup>- and Ca<sup>2+</sup>-ATPase activities in the duodenum of female rats
Other Contributor(s)
Abstract
Prolactin has recently been shown to directly stimulate 2 components of the active duodenal calcium transport in female rats, i.e., solvent drag-induced and transcellular-active calcium transport. Since the basolateral Na+/K+- and Ca2+-ATPases, respectively, play important roles in these 2 transport mechanisms, the present study aimed to examine the direct actions of prolactin on the activities of both transporters in sexually mature female Wistar rats. The results showed that 200, 400, and 800 ng/mL prolactin produced a significant increase in the total ATPase activity of duodenal crude homogenate in a dose-dependent manner within 60 min (i.e., from a control value of 1.53 ± 0.13 to 2.29 ± 0.21 (p < 0.05), 2.68 ± 0.19 (p < 0.01), and 3.92 ± 0.33 (p < 0.001) μmol Pi·(mg protein)-1·min-1, respectively). Activity of Na+/K+-ATPase was increased by 800 ng/mL prolactin from 0.17 ± 0.03 to 1.18 ± 0.29 μmol Pi·(mg protein)-1·min-1(p < 0.01). Prolactin at doses of 400 and 600 ng/mL also significantly increased the activities of Ca2+-ATPase in crude homogenate from a control value of 0.84 ± 0.03 to 1.75 ± 0.29 (p < 0.05), and 2.30 ± 0.37 (p < 0.001) μmol Pi·(mg protein)-1·min-1. When the crude homogenate was purified for the basolateral membrane, the Na+/K+-ATPase activities were elevated 10-fold. In the purified homogenate, 800 ng/mL prolactin increased Na+/K+-ATPase activity from 1.79 ± 0.38 to 2.63 ± 0.44 μmol Pi·(mg protein)-1·min-1(p < 0.05), and Ca2+-ATPase activity from 0.08 ± 0.14 to 2.03 ± 0.23 μmol Pi·(mg protein)-1·min-1(p < 0.001). Because the apical calcium entry was the first important step for the transcellular active calcium transport, the brush border calcium uptake was also investigated in this study. We found that, 8 min after being directly exposed to 800 ng/mL prolactin, the brush border calcium uptake into the duodenal epithelial cells was increased from 0.31 ± 0.02 to 0.80 ± 0.28 nmol·(mg protein)-1(p < 0.05). It was concluded that prolactin directly and rapidly enhanced the brush border calcium uptake as well as the activities of the basolateral Na+/K+- and Ca2+-ATPases in the duodenal epithelium of female rats. These findings explained the mechanisms by which prolactin stimulated duodenal active calcium absorption. © 2006 NRC Canada.