Regulation of Intestinal Calcium Transport

Khanal, Ramesh C.; Nemere, Ilka

doi:10.1146/annurev.nutr.010308.161202

Cited by 93 publications

(94 citation statements)

References 134 publications

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“…An L-type voltage-gated Ca 2+ channel on the brush border of enterocytes is involved in Ca 2+ uptake in Atlantic cod (Larsson et al, 1998). Ca 2+ uptake could occur similar to the transcellular model proposed for the gill, or from a variety of processes, such as vesicular-mediated transport or paracellular pathways (Khanal and Nemere, 2008;Perez et al, 2008).…”

Section: Role Of Ecac In Camentioning

confidence: 88%

The influence of environmental calcium concentrations on calcium flux, compensatory drinking and epithelial calcium channel expression in a freshwater cartilaginous fish

Allen

Weihrauch

Grandmaison

et al. 2011

Journal of Experimental Biology

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SUMMARYCalcium metabolism and mRNA levels of the epithelial calcium channel (ECaC) were examined in a freshwater cartilaginous fish, the lake sturgeon Acipenser fulvescens. Lake sturgeon were acclimated for ≥2 weeks to 0.1 (low), 0.4 (normal) or 3.3 (high) mmoll -1 environmental calcium. Whole-body calcium flux was examined using 45Ca as a radioactive marker. Net calcium flux was inward in all treatment groups; however, calcium influx was greatest in the low calcium environment and lowest in the high calcium environment, whereas efflux had the opposite relationship. A significant difference in the concentration of 45 Ca in the gastrointestinal tract (GIT) of fish in the low calcium environment led to the examination of drinking rate and calcium flux across the anterior-middle (mid) intestine. Drinking rate was not different between treatments; however, calcium influx across the midintestine in the low calcium treatment was significantly greater than that in both the normal and high calcium treatments. The lake sturgeon ECaC was 2831bp in length, with a predicted protein sequence of 683 amino acids that shared a 66% identity with the closest sequenced ECaCs from the vertebrate phyla. ECaC mRNA levels were examined in the gills, kidney, pyloric caeca, midintestine and spiral intestine. Expression levels were highest in the gills, then the kidneys, and were orders of magnitude lower in the GIT. Contrary to existing models for calcium uptake in the teleost gill, ECaC expression was greatest in high calcium conditions and kidney ECaC expression was lowest in low calcium conditions, suggesting that cellular transport mechanisms for calcium may be distinctly different in these freshwater cartilaginous fishes.

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Section: Role Of Ecac In Camentioning

confidence: 88%

The influence of environmental calcium concentrations on calcium flux, compensatory drinking and epithelial calcium channel expression in a freshwater cartilaginous fish

Allen

Weihrauch

Grandmaison

et al. 2011

Journal of Experimental Biology

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“…Vitamin D deficiency has also been shown to impair insulin secretion in experimental studies [3,4]. Moreover, because vitamin D facilitates calcium absorption in the intestines [29], vitamin D and calcium may act synergistically to reduce the risk of type 2 diabetes. Dairy foods rich in calcium may decrease the risk of diabetes through calcium-related mechanisms.…”

Section: Discussionmentioning

confidence: 99%

Calcium, vitamin D and dairy intake in relation to type 2 diabetes risk in a Japanese cohort

et al. 2009

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Aims/hypothesis Calcium and vitamin D have been implicated in the development of type 2 diabetes, but epidemiological evidence is limited. We examined prospectively the relation of calcium and vitamin D intake to type 2 diabetes risk in a Japanese cohort. Methods Participants were 59,796 middle-aged and older men and women, who participated in the Japan Public Health Center-based Prospective Study and had no history of type 2 diabetes or other serious diseases. Dietary intake of calcium and vitamin D were estimated using a validated food frequency questionnaire. Logistic regression was used to assess the association between intake of these nutrients and self-reported newly diagnosed type 2 diabetes. Results During a 5 year follow-up, 1,114 cases of type 2 diabetes were documented. Overall, calcium intake was not associated with a significantly lower risk of type 2 diabetes; the multivariable odds ratio for the highest vs lowest quartiles was 0.93 (95% CI 0.71-1.22) in men and 0.76 (95% CI 0.56-1.03) in women. However, among participants with a higher vitamin D intake, calcium intake was inversely associated with diabetes risk; the odds ratio for the highest vs lowest intake categories was 0.62 (95% CI 0.41-0.94) in men and 0.59 (95% CI 0.38-0.91) in women. Dairy food intake was significantly associated with a lower risk of type 2 diabetes in women only. Conclusions/interpretation Calcium and vitamin D may not be independently associated with type 2 diabetes risk. Our finding suggesting a joint action of these nutrients against type 2 diabetes warrants further investigation.

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“…The first model is based on a passive diffusion tunneling through the endoplasmatic reticulum, vesicular transport along the microtubules involving lysosomes, and finally, facilitated diffusion. According to the second model, Ca 2+ -transporting cells utilize lysosomes to sequester Ca 2+ and facilitate its movement to the basolateral membrane [35]. The apical Ca 2+ influx through TRPV5 initiates the disruption of the actin cytoskeleton and the formation of Ca 2+ -enriched endocytic vesicles, which are transported along the microtubules and some fuse with lysosomes [46].…”

Section: Introductionmentioning

confidence: 99%

Active Ca2+ reabsorption in the connecting tubule

Boros

Bindels

Hoenderop

2008

Pflugers Arch - Eur J Physiol

114

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The kidney plays a crucial role in the maintenance of the body calcium (Ca 2+ ) balance. Ca 2+ is an essential ion in all organisms and participates in a large variety of structural and functional processes. In mammals, active tubular Ca 2+ reabsorption is restricted to the distal part of the nephron, i.e., the late distal convoluted (DCT2) and the connecting tubules (CNT), where approximately 10-15% of the total Ca 2+ is reabsorbed. This active transcellular transport is hallmarked by the transient receptor potential vanilloid 5 (TRPV5) epithelial Ca 2+ channel, regulated by an array of events, and mediated by hormones, including 1,25-dihydroxyvitamin D 3 , parathyroid hormone, and estrogen. Novel molecular mechanisms have been identified, such as the direct regulatory effects of klotho and tissue kallikrein on the abundance of TRPV5 at the apical membrane. The newly discovered mechanisms could provide potential pharmacological targets in the therapy of renal Ca 2+ wasting. This review discusses the three basic molecular steps of active Ca 2+ reabsorption in the DCT/CNT segments of the nephron, including apical entry, cytoplasmic transport, and basolateral extrusion of Ca 2+ . In addition, an overview of the recently identified mechanisms governing this active Ca 2+ transport through the DCT2/CNT epithelial cells will be presented.

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Regulation of Intestinal Calcium Transport

Cited by 93 publications

References 134 publications

The influence of environmental calcium concentrations on calcium flux, compensatory drinking and epithelial calcium channel expression in a freshwater cartilaginous fish

The influence of environmental calcium concentrations on calcium flux, compensatory drinking and epithelial calcium channel expression in a freshwater cartilaginous fish

Calcium, vitamin D and dairy intake in relation to type 2 diabetes risk in a Japanese cohort

Active Ca2+ reabsorption in the connecting tubule

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