Expression patterns of intestinal calcium transport factors and ex-vivo absorption of calcium in horses.
Authors: Sprekeler Nele, Müller Tobias, Kowalewski Mariusz P, Liesegang Annette, Boos Alois
Journal: BMC veterinary research
Summary
# Editorial Summary: Intestinal Calcium Transport in Horses Calcium absorption physiology differs markedly between horses and other species, yet the mechanisms governing this process in equines remain poorly characterised. Researchers examined expression patterns of key proteins involved in active, vitamin D-dependent calcium transport—specifically vitamin D receptor (VDR), calbindin-D9k (CB) and the TRPV6 channel—alongside functional calcium absorption capacity in equine intestinal tissue, using quantitative RT-PCR, Western blotting, immunohistochemistry and the Ussing chamber electrophysiology technique. The study revealed species-specific distribution of these calcium-handling proteins throughout the small intestine and quantified regional variation in transcellular calcium transport capability. Understanding these expression patterns and absorption characteristics is important for practitioners developing evidence-based feeding strategies, particularly when formulating calcium supplementation protocols or addressing absorption-related metabolic disorders, as equine intestinal calcium handling does not simply mirror mechanisms observed in other domesticated species.
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Practical Takeaways
- •Understanding equine-specific calcium absorption physiology is essential when formulating mineral nutrition protocols, as horses have fundamentally different calcium metabolism from other species
- •Intestinal region-specific differences in calcium transport protein expression suggest that overall digestive and absorption capacity varies along the GI tract
- •Vitamin D status directly influences transcellular calcium absorption capacity in horses and should be considered in nutritional management strategies
Key Findings
- •Horses demonstrate distinct calcium absorption mechanisms involving vitamin D-dependent transcellular pathways with expression of VDR, TRPV6, and calbindin-D9k in the small intestine
- •Calcium transport protein expression patterns differ between equine intestinal segments and regions within segments
- •Ex-vivo calcium absorption in horses was measurable using Ussing chamber technique, confirming functional transcellular transport capacity