Blood glucose clearance after feeding and exercise in polysaccharide storage myopathy.
Abstract: Polysaccharide storage myopathy (PSSM) in Quarter Horses (QH) and QH crosses is a glycogen storage disorder in which blood glucose clearance and insulin sensitivity, following an i.v. or oral glucose challenge, are enhanced. Exercise is known also to enhance glucose uptake into skeletal muscle in many animal species. Therefore, the purpose of this study was to compare the effect of exercise on glucose clearance in PSSM and control horses when an oral carbohydrate meal (8 Mcal sweet feed) was fed following either 12 h fasting alone (NEX protocol) or following fasting and a standard exercise protocol (EX protocol). In the NEX protocol, horses fasted 12 h and then were fed 8 megacalories (Mcal) of sweet feed (2.3 kg). In the EX protocol, horses were fed sweet feed 2 h after an exercise test (SET). Blood glucose was analysed for < 480 min after feeding. Muscle biopsies were taken before and after the EX protocol. With the NEX protocol, the mean of all blood glucose and insulin concentrations were significantly lower in fed-PSSM horses than controls (P < 0.013). The EX protocol in control horses caused a less pronounced percentage change in glucose concentration from baseline following feeding compared to the NEX protocol (mean peak EX 26.5% vs. NEX 70.2%, respectively) (P < 0.0003). In PSSM horses, the EX protocol also resulted in a lower percent change in glucose concentration following feeding compared to the NEX protocol (44.7 vs. 67.5%, respectively) (P = 0.021). The magnitude of the difference in percentage change of blood glucose concentration with the EX protocol was less in PSSM than that seen for controls (mean peak PSSM-EX 44.7% vs. 26.5% for controls, respectively) (P < 0.006). No significant differences in the insulin:glucose ratios were found for control horses between NEX and EX. In PSSM horses, the insulin:glucose ratio was significantly increased in the EX vs. NEX. In conclusion, exercise in normal horses results in enhanced glucose clearance following feeding without altering insulin:glucose ratios. At rest, PSSM horses have lower insulin:glucose ratios after feeding than normal horses, however, exercise in PSSM horses significantly increases insulin:glucose ratios. This may explain the beneficial effect of daily exercise for preventing rhabdomyolysis in horses with PSSM.
Publication Date: 2000-02-05 PubMed ID: 10659276DOI: 10.1111/j.2042-3306.1999.tb05242.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research investigates the effects of exercise on blood glucose clearance in horses with Polysaccharide Storage Myopathy (PSSM). It found that exercise enhances glucose clearance but increases the insulin-to-glucose ratio in PSSM horses, offering insight into why daily exercise prevents muscle damage in these horses.
Research Overview
- The study centers on Polysaccharide Storage Myopathy (PSSM), a glycogen storage disease common in Quarter Horses (QH) and QH crosses. In these horses, blood glucose clearance and insulin sensitivity improve after an oral or intravenous glucose challenge.
- The researchers aimed to determine how exercise affects glucose clearance in PSSM horses compared to control horses, when fed a carbohydrate meal after either 12 hours of fasting only or fasting with a standard exercise routine.
- The study used two protocols: the NEX protocol (No Exercise) where horses were fasted for 12 hours then fed 8 Mcal (megacalories) of sweet feed, and the EX protocol (Exercise) where horses were fed sweet feed 2 hours after an exercise test. Blood glucose was then tested for 480 minutes following feeding.
- Muscle biopsies were additionally taken before and after the EX protocol to understand the tissue level impacts of the exercise.
Key Findings
- Under the NEX protocol, PSSM horses had significantly lower average blood glucose levels and insulin concentrations compared to controls.
- In control horses, the EX protocol led to lower changes in glucose concentrations after feeding compared to the NEX protocol. PSSM horses had similar results under the EX protocol compared to the NEX protocol, but with less drastic difference.
- There were no significant differences noted in the insulin-to-glucose ratios between the NEX and EX protocols for control horses. However, for PSSM horses, the insulin-to-glucose ratio increased significantly in the EX protocol compared to the NEX protocol.
Conclusions
- The study concluded that in normal horses, exercise enhances glucose clearance following feeding without altering insulin-to-glucose ratios.
- For PSSM horses, even though they have lower insulin-to-glucose ratios after feeding at rest, exercise significantly increases this ratio.
- These findings could explain the known benefit of daily exercise in preventing rhabdomyolysis (muscle breakdown) in PSSM horses as the increased insulin-to-glucose ratio could facilitate the regulation of glucose more effectively, consequently mitigating muscle damages.
Cite This Article
APA
De La Corte FD, Valberg SJ, Mickelson JR, Hower-Moritz M.
(2000).
Blood glucose clearance after feeding and exercise in polysaccharide storage myopathy.
Equine Vet J Suppl(30), 324-328.
https://doi.org/10.1111/j.2042-3306.1999.tb05242.x Publication
Researcher Affiliations
- Department of Clinical and Population Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul 55108, USA.
MeSH Terms
- Animals
- Blood Glucose / metabolism
- Dietary Carbohydrates / administration & dosage
- Female
- Food
- Glycogen Storage Disease / veterinary
- Horse Diseases / blood
- Horses
- Male
- Muscles / metabolism
- Physical Conditioning, Animal
- Polysaccharides / metabolism
Citations
This article has been cited 1 times.- McCue ME, Valberg SJ, Miller MB, Wade C, DiMauro S, Akman HO, Mickelson JR. Glycogen synthase (GYS1) mutation causes a novel skeletal muscle glycogenosis. Genomics 2008 May;91(5):458-66.
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