scholarly journals ATP-linked calcium transport in cells and membrane vesicles of Streptococcus faecalis.

1978 ◽  
Vol 253 (7) ◽  
pp. 2085-2092 ◽  
Author(s):  
H. Kobayashi ◽  
J. Van Brunt ◽  
F.M. Harold
Keyword(s):  
Calcium Transport ◽  
Membrane Vesicles ◽  
Streptococcus Faecalis ◽  
In Cells

Calcium transport by rat duodenal villus and crypt basolateral membranes

1987 ◽  
Vol 252 (2) ◽  
pp. G170-G177 ◽  
Author(s):  
J. R. Walters ◽  
M. M. Weiser
Keyword(s):  
Vitamin D ◽  
Calcium Transport ◽  
Calcium Uptake ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Calcium Pump ◽  
Cell Fraction ◽  
Basolateral Membranes ◽  
Pump Activity ◽  
Crypt Cells

Rat duodenal cells were isolated sequentially to give fractions enriched for villus and crypt cells. From each of these fractions, basolateral-enriched membrane vesicles were prepared and ATP-dependent calcium uptake was studied. Calcium uptake was sensitive to temperature, was inhibited by vanadate and by A23187, and was lower in vitamin D-deficient animals. In normal animals, calcium transport was approximately twofold greater in villus-tip than in crypt cell-fraction basolateral membranes though the affinity of the uptake for calcium was similar (Km = 0.3 microM). In vitamin D-deficient animals, the crypt-to-villus gradient was reduced, and in all fractions, calcium transport was similar to or lower than that in the crypts of normal animals. Six hours after vitamin D-deficient animals were repleted with 1,25-dihydroxycholecalciferol, a significant increase in calcium transport by everted gut sacs was present; however, basolateral calcium transport was significantly increased in only the mid-villus fractions, and no change was seen in the villus-tip fractions. Thus vitamin D appears necessary for the development of increased basolateral membrane calcium pump activity in duodenal villus cells, but not all cells in vitamin D-deficient rats are able to respond to 1,25-dihydroxycholecalciferol.

Mechanism of regulation of calcium-pumping activity in chick intestine

1992 ◽  
Vol 262 (5) ◽  
pp. G797-G805
Author(s):  
J. Takito ◽  
T. Shinki ◽  
H. Tanaka ◽  
T. Suda
Keyword(s):  
Vitamin D ◽  
Calcium Transport ◽  
Calcium Uptake ◽  
Early Stage ◽  
Basolateral Membrane ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Membrane Vesicles ◽  
Intestinal Calcium Transport ◽  
Pumping Activity

The role of the calcium pump in the stimulation of intestinal calcium transport activity by 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3] was examined in chicks. The in situ intestinal absorption of calcium increased approximately threefold in the duodenum, jejunum, and ileum 6 h after a single injection of 625 ng of 1 alpha,25(OH)2D3 into vitamin D-deficient chicks. The same treatment also increased approximately twofold the rate of ATP-dependent calcium uptake by the basolateral membrane vesicles (BL) isolated from those three sites. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that a Mg(2+)-dependent calcium-stimulated phosphorylated intermediate with an apparent molecular mass of 105 kDa appeared in the BL. The 1 alpha,25(OH)2D3 treatment gave no change in the levels of the intermediate. Pretreatment of the BL with alkaline phosphatase decreased the calcium uptake by the BL isolated from 1 alpha,25(OH)2D3-treated chicks, but it had little effect on the uptake by the BL from vitamin D-deficient chicks. These results suggest that at an early stage of the 1 alpha,25(OH)2D3-induced intestinal calcium transport process, the vitamin regulates the calcium-pumping activity of chick intestinal BL by phosphorylation and dephosphorylation but not by a stoichiometric change in the pump.

Sign in / Sign up

Export Citation Format

Share Document