Effects of induction of capacitative calcium entry on equine laminar microvessels.
Abstract: To determine the effects of induction of capacitative Ca2+ entry on tone in equine laminar arteries and veins. Methods: Laminar arteries and veins from 6 adult mixed-breed horses. Methods: Arteries and veins were isolated and mounted on small vessel myographs for the measurement of isometric tension. Capacitative Ca2+ entry was induced by incubating the vessels with the specific Ca2+-ATPase inhibitor thapsigargin (100nM) in a Ca2+-free physiologic salt solution. Capacitative Ca2+ entry-associated contractile responses were determined by the subsequent addition of 2mM Ca2+ to the solution bathing the vessels; in some experiments, either the voltage-gated Ca2+ blocker diltiazem (10microM) or the putative capacitative Ca2+ entry inhibitor trifluoromethylphenylimidazole (300microM) was added to the bathing solution 15 minutes prior to a second 2mM Ca2+ exposure. The Sr2+ permeability of the capacitative Ca2+ entry pathway in laminar vessels was assessed by exposing the vessels to 4mM Sr2+ after induction of capacitative Ca2+ entry with thapsigargin. Results: Induction of capacitative Ca2+ entry elicited robust contractile responses in laminar veins but did not increase tone in laminar arteries. In laminar veins, capacitative Ca2+ entry-induced contractile responses were unaffected by preincubation with diltiazem, attenuated by trifluoromethylphenylimidazole, and were impermeable to Sr+. Conclusions: Results indicated that induction of capacitative Ca2+ entry elicits vasoconstriction in equine laminar veins but not in laminar arteries and should therefore be considered a potential mechanism by which selective venoconstriction occurs in horses during the development of acute laminitis.
Publication Date: 2005-12-13 PubMed ID: 16334943DOI: 10.2460/ajvr.2005.66.1877Google Scholar: Lookup
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- Journal Article
- Research Support
- U.S. Gov't
- Non-P.H.S.
Summary
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The research conducted an experiment to understand how the induced movement of calcium ions affects the tension in blood vessels of horses. It found that this process causes contraction in the veins of a horse’s hoof, but not in the arteries, suggesting a possible mechanism behind a serious hoof disease.
Research Method
- The study was conducted on the blood vessels from the laminar region (part of the hoof) of six adult, mixed-breed horses.
- The researchers isolated arteries and veins, then mounted them on a device which can measure their isometric tension, to understand how they react under stress.
- A process called capacitative calcium entry (where calcium ions are forced into the cells) was initiated using a specific chemical inhibitor (thapsigargin).
- The researchers then determined what effect reintroducing calcium to the surrounding environment had on the contractile responses of the blood vessels.
- To examine the role of different elements in the process, in some cases additional chemicals were added 15 minutes before reintroduction of calcium.
- A chemical called Strontium (Sr2+) was also used to understand whether it can pass through the same pathway as calcium during the capacitative calcium entry.
Findings
- The experiment revealed that inducing capacitative calcium entry caused significant contraction in the veins, but not in the arteries.
- In the vein samples, the contractions induced by capacitative calcium entry were not affected by one of the chemicals (diltiazem), were lessened by another (trifluoromethylphenylimidazole), and didn’t allow Strontium to pass through.
Conclusions
- The study concluded that inducing capacitative calcium entry can cause veins in a horse’s hoof to contract noticeably, but the same process does not affect arteries.
- This phenomenon demands consideration as a potential explanation for the selective contraction of veins in the development of acute laminitis, a painful and serious hoof disease in horses.
Cite This Article
APA
Robertson TP, Peroni JF, Lewis SJ, Moore JN.
(2005).
Effects of induction of capacitative calcium entry on equine laminar microvessels.
Am J Vet Res, 66(11), 1877-1880.
https://doi.org/10.2460/ajvr.2005.66.1877 Publication
Researcher Affiliations
- Department of Physiology and Pharmacology, Institute of Comparative Medicine, University of Georgia, Athens 30602-7389, USA.
MeSH Terms
- Animals
- Arteries / drug effects
- Arteries / physiology
- Calcium / physiology
- Calcium Channel Blockers / pharmacology
- Diltiazem / pharmacology
- Enzyme Inhibitors / pharmacology
- Forelimb / blood supply
- Hoof and Claw / blood supply
- Horses / physiology
- In Vitro Techniques
- Mice
- Muscle, Smooth, Vascular / drug effects
- Muscle, Smooth, Vascular / physiology
- Myography / veterinary
- Strontium / physiology
- Thapsigargin / pharmacology
- Vasoconstriction / drug effects
- Vasoconstriction / physiology
- Veins / drug effects
- Veins / physiology
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