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The Journal of physiology1986; 377; 25-35; doi: 10.1113/jphysiol.1986.sp016174

Blood flow to the respiratory and limb muscles and to abdominal organs during maximal exertion in ponies.

Abstract: Using radionuclide-labelled microspheres, 15 micron in diameter, we studied blood flow in the respiratory muscles (diaphragm and intercostal muscles), abdominal organs (adrenal glands, kidneys, pancreas, spleen and the small and large intestines), muscles of propulsion (gluteus medius and biceps femoris), and other working (triceps brachii and longissimus dorsi lumborum) and non-working (temporal and masseter) muscles of ponies at rest and during maximal exercise performed on a treadmill. During maximal exercise heart rate, whole body O2 consumption, cardiac output and mean aortic pressure increased 4.4-fold, 38-fold, 8-fold and 1.5-fold of their resting values, respectively. During maximal exertion arterial CO2 tension and arterial pH decreased while arterial O2 content increased by 58% due to a 59.6% rise in haemoglobin concentration. Arterial O2 tension decreased somewhat and the calculated alveolar to arterial O2 tension gradient widened during exertion. During maximal exertion blood flow in the adrenal glands increased while that in the kidneys, spleen, pancreas, small intestine and colon decreased precipitously. Thus ponies exhibited intense vasoconstriction in the renal and splanchnic vascular beds, similar to that reported in man but not in exercising dogs. During maximal exertion stride (and hence respiratory) frequency of galloping ponies was 138 +/- 3 min-1, and the blood flow and O2 delivery in the diaphragm were not different from those in other strenuously working muscles, namely gluteus medius, biceps femoris (muscles of propulsion) and triceps brachii. Blood flow in the intercostal muscles was only 54% of that in the diaphragm at rest, but with maximal exercise it registered a marked increment and the perfusion became similar to that in the longissimus dorsi lumborum, a powerful extensor of the back and loins.
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Publication Date: 1986-08-01 PubMed ID: 3795089PubMed Central: PMC1182820DOI: 10.1113/jphysiol.1986.sp016174Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research article investigates how blood flow changes in various muscles and organs in ponies during intense exercise, using radionuclide-labelled microspheres. It found that significant changes occur in heart rate, oxygen consumption, arterial oxygen content, and blood flow in various muscles and organs during maximal exertion.

Research Methods and Procedure

  • The study was conducted on ponies at rest and during maximal exercise performed on a treadmill.
  • Radiolabelled microspheres were injected into the left heart to study the blood flow rates in various muscles and organs. The microspheres are 15 microns in diameter and get caught up in the capillaries where they emit radiation that can be detected and measured.

Key Findings of the Study

  • Heart rate, oxygen consumption and mean aortic pressure increased significantly during maximal exercise, by 4.4-fold, 38-fold and 1.5-fold, respectively, of their resting values.
  • The arterial carbon dioxide tension decreased, arterial oxygen content increased by 58% due to a 59.6% increase in hemoglobin concentration and the arterial oxygen tension decreased during exertion.
  • The blood flow in adrenal glands increased, while it decreased in kidneys, spleen, pancreas, and intestines. It showed that there was intense vasoconstriction (narrowing of blood vessels) in the renal and splanchnic vascular beds, an effect seen in humans but not in dogs during exercise.
  • Respiratory frequency increased to 138 +/- 3 min-1 during exercise. The blood flow and oxygen delivery to the diaphragm and working muscles (such as gluteus medius, biceps femoris, and triceps brachii) did not change significantly. This suggests that these muscles were able to adapt to the increased energy demand.
  • Blood flow in the intercostal muscles (which assist in breathing) increased during maximal exercise, reaching a level similar to that in the longissimus dorsi lumborum, a powerful back and loin extensor. This suggests that these muscles play important roles in maintaining the ponies’ efforts during maximal exercise.

Implications of the Findings

  • This study sheds light on the physiological adaptations that occur during intense exercise in ponies.
  • The observed changes in blood flow during exercise can be beneficial in developing training protocols for optimal performance in equestrian sports.
  • The clear similarity of some responses to exercise between ponies and humans, particularly the vasoconstriction in the renal and splanchnic vascular beds, may indicate shared evolutionary responses to intense physical activity and may even have research implications for human physiology study.

Cite This Article

APA
Manohar M. (1986). Blood flow to the respiratory and limb muscles and to abdominal organs during maximal exertion in ponies. J Physiol, 377, 25-35. https://doi.org/10.1113/jphysiol.1986.sp016174

Publication

The Journal of physiology
ISSN: 0022-3751
NlmUniqueID: 0266262
Country: England
Language: English
Volume: 377
Pages: 25-35

Researcher Affiliations

Manohar, M

    MeSH Terms

    • Abdomen / blood supply
    • Animals
    • Forelimb / physiology
    • Hemodynamics
    • Hindlimb / physiology
    • Horses / physiology
    • Muscles / blood supply
    • Oxygen / blood
    • Physical Exertion
    • Regional Blood Flow
    • Respiratory Muscles / blood supply

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    Citations

    This article has been cited 24 times.
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