Renal and systemic hemodynamic responses to sustained submaximal exertion in horses

K. W. Hinchcliff, K. H. McKeever, L. M. Schmall, C. W. Kohn, W. W. Muir

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


We investigated the effects of 1 h or sustained submaximal exertion on the renal and systemic hemodynamics of six horses. The horses ran on a treadmill at a speed that produced heart rates of 55-60% of each horse's maximum heart rate. Exertion produced heart rates of 121 ± 6.6 and 126 ± 6.1 (SE) beats/min after 15 and 60 min, respectively. Cardiac output increased significantly (P < 0.05) from 70.1 ± 3.1 to 246.2 ± 4.7 ml·min-1·kg body wt-1 after 15 min of exertion and thereafter did not change. There was no significant change from rest in p-aminohippuric acid and creatinine clearances, filtration fraction, or renal blood flow during exertion. Plasma total solid concentration and hematocrit increased by 3.8 and 8.6%, respectively, between 20 and 60 min of exertion. Pulmonary artery temperature increased significantly from 37.6°C at rest to 38.6°C at 60 min of exertion. This study demonstrates the ability of the horse to maintain renal hemodynamics similar to resting values and systemic hemodynamics at steady-state values despite hemoconcentration and increased body temperature during sustained submaximal exertion.

Original languageEnglish (US)
Pages (from-to)R1177-R1183
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Issue number5 27-5
StatePublished - 1990
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physiology
  • Physiology (medical)


  • creatinine clearance
  • p-aminohippuric acid clearance
  • renal blood flow


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