Blood flow to respiratory, cardiac, and limb muscles in dogs during graded exercise

D. E. Fixler, J. M. Atkins, J. H. Mitchell, L. D. Horwitz

Research output: Chapter in Book/Report/Conference proceedingChapter

63 Scopus citations


The distribution of cardiac output was analyzed in six dogs, with the animals at rest and running on a level treadmill for 3 min at 3-4 mph (mild exercise) and 3 min at 6-8 mph (moderate exercise). Organ flows were measured using 25 μm diam radioactive microspheres. Cardiac output averaged 2.5, 4.6, and 5.7 liters/min, for rest, mild exercise, and moderate exercise, respectively. The greatest change was in diaphragmatic flow which increased by 275% with mild exercise and 500% with moderate exercise. Flow to intercostal muscles increased by 160 and 186%, to the exercising gastrocnemius muscle by 153 and 224%, and to cardiac muscle by 57 and 109% during mild and moderate exercise, respectively. Renal and cerebral flows did not change significantly. Significant decreases in flow occurred in the small and large intestines duing moderate exercise. It is concluded that the increase in cardiac output during submaximal exercise was redistributed in a manner which limited flow to the brain, intestines, and kidneys and increased flow to the diaphragm, heart, and limb muscles.

Original languageEnglish (US)
Title of host publicationAmerican Journal of Physiology
StatePublished - 1976

ASJC Scopus subject areas

  • Medicine(all)


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