Intestinal Maturation: Calcium Transport by Basolateral Membranes

Dannan, Ghazi A.; Arab, Noushin; Kikuchi, Kazuhiro

doi:10.1203/00006450-198703000-00010

Cited by 16 publications

(7 citation statements)

References 6 publications

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“…An ATP-dependent calmodulin-regulated mechanism has been described in the basolateral membranes of the enterocyte (23). Recently, we have described a similar mechanism in suckling rat basolateral membranes (12). Our current data suggest that vitamin D administration enhanced the V, , , of the ATP-dependent calcium transport system in the basolateral membranes of the suckling and adolescent rats.…”

Section: Discussionsupporting

confidence: 75%

Calcium Transport by Plasma Membranes of Enterocytes during Development: Role of 1,25-(OH)2 Vitamin D3

Leonard

Pietsch

1988

Pediatr Res

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ABSTRACT. Calcium transport across the intestinal enterocytes represents an entry process at the brush border membranes and an ATP-dependent exit process located at the basolateral membranes. Both processes exhibit developmental changes. The present studies were designed to define the role of vitamin D in calcium transport during maturation. Brush border and basolateral membranes from vitamin D-deficient suckling and adolescent rats were used to study calcium entry and exit. 1,25-(OH)2 vitamin D3 administration enhanced calcium entry at the brush border membranes of suckling and adolescent rats. The increase in calcium uptake in both age groups was secondary to an increase in maximal transport capacity (V,,,) rather than in K,. In suckling rat brush border membranes, 1,25-(0H)z vitamin D3 treatment increased the V, , , from 1.0 + 0.1 to 1.8 f 0.2 nmollmg protein17 s ( p < 0.01), whereas in adolescent rats, V, , , increased from 1.5 f 0.1 to 2.5 f 0.3 nmollmg protein17 s ( p < 0.01). K, values were not altered.Similarly, 1,25-(OH)2 vitamin D3 administration enhanced ATP-dependent calcium exit at the basolateral membranes of both suckling and adolescent rats. V, , , of ATP-dependent calcium uptake by basolateral membranes of suckling rats increased from 0.5 f 0.05 to 0.81 f 0.06 nmollmg protein120 s ( p < 0.01) whereas in adolescent rats, V , increased from 0.3 f 0.03 to 0.6 f 0.04 nmol/mg protein/ 20 s ( p < 0.001). K, values were not altered. The current studies indicate that 1,25-(0H)z vitamin D3 stimulates calcium entry and exit across the enterocytes during maturation. (Pediatr Res 24:338-341, 1988)

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Section: Discussionsupporting

confidence: 75%

Calcium Transport by Plasma Membranes of Enterocytes during Development: Role of 1,25-(OH)2 Vitamin D3

Leonard

Pietsch

1988

Pediatr Res

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“…Therefore, our studies clearly demonstrate that calcium was transported into the intravesicular space rather than bound to the external surface of the vesicles. The characteristics and ontogeny of the transport systems for intestinal basolateral and microsomal uptake is quite different from that of Golgi uptake (26,27), whereas calcium uptake in basolateral and microsomal membrane vesicles decreased with advancing age, the opposite is characteristic of uptake by Golgi vesicles. The ATP-dependent mechanism of calcium transport by intestinal Golgi vesicles in adult rats has been described recently (28).…”

Section: Discussionmentioning

confidence: 76%

“…As seen in Figure 3, calcium release occurred rapidly in the presence of the ionophore suggesting that calcium was present in the intravesicular space rather than bound. We have used similar experiments for brush border (25) and basolateral membrane vesicles (26) to show that calcium was present in the intravesicular space. Therefore, our studies clearly demonstrate that calcium was transported into the intravesicular space rather than bound to the external surface of the vesicles.…”

Section: Discussionmentioning

confidence: 99%

Vitamin D-Regulated, ATP-Dependent Calcium Transport by Intestinal Golgi Vesicles during Maturation in the Rat

Arab¹

1989

Pediatr Res

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ABSTRACT. The developmental aspects of Calcium uptake by intestinal Golgi vesicles was determined using highly purified Golgi vesicles from enterocytes of suckling (2 wk old), weanling (3 wk old), and adolescent (6 wk old) rats. Calcium uptake by Golgi vesicles at all age groups represented transport into the intravesicular space as evident by temperature dependency and by calcium ionophore A23187-induced calcium efflux studies. Calcium uptake was driven by ATP at all age groups, however, maximal uptake at 15 min was significantly greater in Golgi vesicles of adolescent rats compared to mean values in Golgi vesicles of suckling rats (p < 0.01). Calcium uptake in the absence of ATP was minimal. The requirement for the adenine base and the hydrolysis of the ,f3-y-phosphodiester was tested by replacement of ATP in the incubation media by CTP and the nonhydrolyzable ATP analogue, adenylyl-(@-y-methylendiphosphonate). Both agents had no stimulatory effect on calcium uptake. Calcium uptake was linear up to 40 s. Kinetic parameters of calcium uptake at free calcium concentrations of 0.04 to 1.0 pM showed a maximal transport capacity of 0.99 + 0.05, 0.55 f 0.04, and 0.29 f 0.03 nmollmg protein115 s for adolescent, weanling, and suckling rats, respectively. Km values were 0.16 f 0.02, 0.12 + 0.03, and 0.07 2 0.02 pM for adolescent, weanling and suckling rats, respectively. Km and V,,, values were significantly different between adolescent and suckling rats (p < 0.01). The calcium regulatory protein calmodulin has no effect on calcium uptake by Golgi vesicles. Vitamin D deficiency in all age groups decreased ATP-dependent calcium uptake. Administration of 1,25-(OH)z vitamin D3 8 h before death enhanced ATP-dependent calcium uptake in all age groups studied. This enhancement was the result of increase in maximal transport capacity of ATP-dependent calcium uptake. This study demonstrates a vitamin D-regulated ATP-driven calcium uptake by intestinal Golgi vesicles at all age groups including the suckling period. This transport system shows developmental patterns in regard to its kinetic parameters. (Pediatr Res 26: 58-62, 1989) Abbreviations 1,25(0H)2 D3, 1,25(OH)2 vitamin D3 AMP-PCP, adenylyl-(@-r-methylendiphosphonate)

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“…Previous studies have shown the presence of ATP-dependent and Ca2+/Na+ exchange processes in rat jejunal basolateral membranes (26)(27)(28). Validation studies utilizing marker enzyme enrichment and lack of effective sodium gradient on D-glucose uptake demonstrated biochemical and functional purity of the BLMV in both SHR and WKY rats.…”

Section: Discussionmentioning

confidence: 87%

“…Previous studies have shown the presence of ATP-dependent and Ca2+/Na+ exchange processes in rat jejunal basolateral membranes (26)(27)(28). Both mechanisms have been described in a variety of tissues including red blood cells (3 l), human placenta (32), adipocyte (25), and cardiac sarcolemma (33), and enterocytes (26,27). This reduction is secondary to a decrease in V,,, rather than in K,,,, indicating that the number and/or activity of the Ca2+/Na+ exchanger is decreased in the SHR compared with WKY rats.…”

Section: Discussionmentioning

confidence: 90%

Intestinal Calcium Transport in Spontaneously Hypertensive Rats (SHR) and Their Genetically Matched WKY Rats

Shibata

1990

Experimental Biology and Medicine

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Calcium transport across the basolateral membranes of the enterocyte represents the active step in calcium translocation. This step occurs by two mechanisms, an ATP-dependent pump and a Ca2+/Na+ exchange process. These studies were designed to investigate these two processes in jejunal basolateral membrane vesicles (BLMV) of the spontaneously hypertensive rats (SHR) and their genetically matched controls, Wistar-Kyoto (WKY) rats. The ATP-dependent calcium uptake was stimulated several-fold compared with no ATP condition in both SHR and WKY, but no differences were noted between rate of calcium uptake in SHR and WKY. Kinetics of ATP-dependent calcium uptake at concentrations between 0.01 and 1.0 microM revealed a Vmax of 0.67 +/- 0.03 nmol/mg protein/20 sec and a Km of 0.2 +/- 0.03 microM in SHR and Vmax of 0.69 +/- 0.12 and a Km of 0.32 +/- 0.14 microM in WKY rats. Ca2+/Na+ exchange in jejunal BLMV of SHR and WKY was investigated in two ways. First, sodium was added to the incubation medium (cis-Na+). Second, Ca2+ efflux from BLMV was studied in the presence of extravesicular Na+ (trans-Na+). Both studies suggest a decreased exchange of calcium and Na+. Kinetic parameters of Na(+)-dependent Ca2+ uptake at concentrations between 0.01 and 1.0 microM exhibited Vmax of 0.05 +/- 0.01 nanmol/mg protein/5 sec and a Km of 0.21 +/- 0.13 microM in SHR and Vmax of 0.11 +/- 0.02 nanmol/mg protein/5 sec and a Km of 0.09 +/- 0.05 in WKY, respectively. These results confirm that the intestinal BLMV of SHR and WKY rats have two mechanisms for calcium extrusion, an ATP-dependent Ca2+ transport process and a Na+/Ca2+ exchange process. The ATP-dependent process appears to be functional in SHR; however, the Ca2+/Na+ exchange mechanism appears to have a marked decrease in its maximal capacity. These findings suggest that calcium extrusion via Ca2+/Na+ is impaired in the SHR, which may lead to an increase in intracellular calcium concentration. These findings may have relevance to the development of hypertension.

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Intestinal Maturation: Calcium Transport by Basolateral Membranes

Cited by 16 publications

References 6 publications

Calcium Transport by Plasma Membranes of Enterocytes during Development: Role of 1,25-(OH)2 Vitamin D3

Calcium Transport by Plasma Membranes of Enterocytes during Development: Role of 1,25-(OH)2 Vitamin D3

Vitamin D-Regulated, ATP-Dependent Calcium Transport by Intestinal Golgi Vesicles during Maturation in the Rat

Intestinal Calcium Transport in Spontaneously Hypertensive Rats (SHR) and Their Genetically Matched WKY Rats

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