Calcium uptake by intestinal brush border membrane vesicles. Comparison with in vivo calcium transport.

Schedl, Harold P.; Wilson, Helen

doi:10.1172/jci112181

Cited by 29 publications

(7 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The apparent affinity constant for CaT1-mediated Ca 2ϩ uptake in Xenopus oocytes of 0.44 mM is in the range of the values previously reported by other investigators in physiological studies of calcium absorption in rat (37)(38)(39), hamster (39), pig (40), and human (41,42) intestines. In agreement with previous predictions (10,15,16), CaT1-mediated Ca 2ϩ transport is driven by the electrochemical gradient of Ca 2ϩ .…”

Section: Discussionsupporting

confidence: 82%

“…The mRNA distribution pattern of CaT1 in rat intestine (Figs. 3 and 4) shows the highest levels in cecum and duodenum and thereby closely matches the results describing segmental heterogeneity of intestinal transcellular calcium absorption (35)(36)(37)(38)(39). The ankyrin repeats predicted from the deduced amino acid sequence of CaT1 suggest that it may be associated with cytoskeletal proteins supporting the microvilli at the apical poles of the absorptive cells in the intestine (24).…”

Section: Discussionsupporting

confidence: 81%

See 1 more Smart Citation

Molecular Cloning and Characterization of a Channel-like Transporter Mediating Intestinal Calcium Absorption

Peng

Chen

Berger

et al. 1999

Journal of Biological Chemistry

568

444

View full text Add to dashboard Cite

Calcium is a major component of the mineral phase of bone and serves as a key intracellular second messenger. Postnatally, all bodily calcium must be absorbed from the diet through the intestine. Here we report the properties of a calcium transport protein (CaT1) cloned from rat duodenum using an expression cloning strategy in Xenopus laevis oocytes, which likely plays a key role in the intestinal uptake of calcium. CaT1 shows homology (75% amino acid sequence identity) to the apical calcium channel ECaC recently cloned from vitamin D-responsive cells of rabbit kidney and is structurally related to the capsaicin receptor and the TRP family of ion channels. Based on Northern analysis of rat tissues, a 3-kilobase CaT1 transcript is present in rat duodenum, proximal jejunum, cecum, and colon, and a 6.5-kilobase transcript is present in brain, thymus, and adrenal gland.

show abstract

Section: Discussionsupporting

confidence: 82%

Section: Discussionsupporting

confidence: 81%

Molecular Cloning and Characterization of a Channel-like Transporter Mediating Intestinal Calcium Absorption

Peng

Chen

Berger

et al. 1999

Journal of Biological Chemistry

568

444

View full text Add to dashboard Cite

show abstract

“…The presence of A23187 enhanced calcium release compared to EGTA indicating the presence ofcalcium in the intravesicularspace. These findings are similar to those ofSchedl and Wilson (14). To determ ine the driving force for calcium uptake by BBMV, uptake studies were done in the presence and absence of sodium gradient .…”

Section: Resultssupporting

confidence: 88%

Developmental Maturation of Calcium Transport by Rat Brush Border Membrane Vesicles

Arab

1987

Pediatr Res

View full text Add to dashboard Cite

ABSTRACT. The developmental aspects of calcium transport across the intestinal brush membrane vesicles was studied utilizing a millipore filtration technique. Calcium transport represented uptake into the intra vesicular space as evidenced by osmolality studies, calcium release by the calcium ionophore A23187, and temperature dependency. Calcium transport in both suckling and adolescent rats appears to occur by a saturable mechanism. Calcium uptake was similar in the presence of sodium and potassium gradients, but decreased in the presence of choline gradient. The imposition of negative membrane potential did not enhance calcium uptake compared to voltage clamp conditions indicating an electroneutral process. The initial rate of calcium uptake was linear up to 15 s. Kinetic analysis of calcium uptake at 7 s showed lower Vmax and lower Km in suckling rats compared to adolescent rats. These studies are the first to demonstrate the maturational aspects of calcium entry at the brush border level and are consistent with our previous kinetic studies utilizing whole tissue. (Pediatr Res 22: 173-176, 1987) Abbreviation BBMV, brush border membrane vesicles Intestinal calcium transport in the rat has been studied by in vivo perfusion techniques (I), everted gut sacs (2), and Ussing chambers (3). These studies provided the overall picture of calcium absorption and has shown that calcium transport occurs by mediated and nonmediated processes (1-3). The mediated process is regulated by 1-25(OHh vitamin D3 the most active polar metabolite of vitamin D (4). The nonmediated process occurs mainly through the paracellular pathway (5). Studies on the developmental aspects of calcium transport using everted gut sacs has shown that the contribution of the non mediated process to the total process of transport declines with age while the mediated component increases (2). The permeability coefficient of calcium in everted gut sacs was higher in suckling rats compared to adolescent rats. Recently studies using isolated membrane vesicles have provided insight into the process of uptake and exit separately. These membrane vesicles otTerthe advantage of setting the experimental conditions at will, i.e. defining the composition of the media at both sides of the membrane without interference with cell metabolism (6). We have recently validated the use of brush border membrane vesicles for the study of developmental aspects of transport (7,8).Using a well-validated technique, we designed the current studies to examine the developmental aspects of calcium transport across the brush border membrane vesicles of the rat intestine. BBMV. Sprague-Dawley rats of varying ages (suckling 14-15 days old and adolescent 42-44 days old) were supplied by Sasco Industries (Omaha, NE) suckling rats were purchased with their mothers. Adolescent rats were shipped directly from the supplier. The animals were housed in the animal care facility. Suckling rats were allowed to suckle freely mother's milk, while adolescent rats were fed standard rat chow (Teklad ...

show abstract

“…This difference in regulation between TRPV’s and PMCA’s is understandable because Ca 2+ transport across the apical membrane is the rate-limiting step [22].…”

Section: Discussionmentioning

confidence: 99%

Chronic High Fructose Intake Reduces Serum 1,25 (OH)2D3 Levels in Calcium-Sufficient Rodents

et al. 2014

View full text Add to dashboard Cite

Excessive fructose consumption inhibits adaptive increases in intestinal Ca2+ transport in lactating and weanling rats with increased Ca2+ requirements by preventing the increase in serum levels of 1,25(OH)2D3. Here we tested the hypothesis that chronic fructose intake decreases 1,25(OH)2D3 levels independent of increases in Ca2+ requirements. Adult mice fed for five wk a high glucose-low Ca2+ diet displayed expected compensatory increases in intestinal and renal Ca2+ transporter expression and activity, in renal CYP27B1 (coding for 1α-hydroxylase) expression as well as in serum 1,25(OH)2D3 levels, compared with mice fed isocaloric glucose- or fructose-normal Ca2+ diets. Replacing glucose with fructose prevented these increases in Ca2+ transporter, CYP27B1, and 1,25(OH)2D3 levels induced by a low Ca2+ diet. In adult mice fed for three mo a normal Ca2+ diet, renal expression of CYP27B1 and of CYP24A1 (24-hydroxylase) decreased and increased, respectively, when the carbohydrate source was fructose instead of glucose or starch. Intestinal and renal Ca2+ transporter activity and expression did not vary with dietary carbohydrate. To determine the time course of fructose effects, a high fructose or glucose diet with normal Ca2+ levels was fed to adult rats for three mo. Serum levels of 1,25(OH)2D3 decreased and of FGF23 increased significantly over time. Renal expression of CYP27B1 and serum levels of 1,25(OH)2D3 still decreased in fructose- compared to those in glucose-fed rats after three mo. Serum parathyroid hormone, Ca2+ and phosphate levels were normal and independent of dietary sugar as well as time of feeding. Thus, chronically high fructose intakes can decrease serum levels of 1,25(OH)2D3 in adult rodents experiencing no Ca2+ stress and fed sufficient levels of dietary Ca2+. This finding is highly significant because fructose constitutes a substantial portion of the average diet of Americans already deficient in vitamin D.

show abstract

Calcium uptake by intestinal brush border membrane vesicles. Comparison with in vivo calcium transport.

Cited by 29 publications

References 26 publications

Molecular Cloning and Characterization of a Channel-like Transporter Mediating Intestinal Calcium Absorption

Molecular Cloning and Characterization of a Channel-like Transporter Mediating Intestinal Calcium Absorption

Developmental Maturation of Calcium Transport by Rat Brush Border Membrane Vesicles

Chronic High Fructose Intake Reduces Serum 1,25 (OH)2D3 Levels in Calcium-Sufficient Rodents

Contact Info

Product

Resources

About