Excess oxygen delivery during muscle contractions in spontaneously hypertensive rats

J. M. Lash, H. G. Bohlen

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

These experiments determined whether a deficit in oxygen supply relative to demand could account for the sustained decrease in tissue PO2 observed during contractions of the spinotrapezius muscle in spontaneously hypertensive rats (SHR). Relative changes in blood flow were determined from measurements of vessel diameter and red blood cell velocity. Venular hemoglobin oxygen saturation measurements were performed by using in vivo spectrophotometric techniques. The relative dilation [times control (xCT)] of arteriolar vessels during contractions was as large or greater in SHR than in normotensive rats (Wistar-Kyoto), as were the increases in blood flow (2 Hz, 3.50 ± 0.69 vs. 3.00 ± 1.05xCT; 4 Hz, 10.20 ± 3.06 vs. 9.00 ± 1.48xCT; 8 Hz, 16.40 ± 3.95 vs. 10.70 ± 2.48xCT). Venular hemoglobin oxygen saturation was lower in the resting muscle of SHR than of Wistar-Kyoto rats (31.0 ± 3.0 vs. 43.0 ± 1.9%) but was higher in SHR after 4- and 8-Hz contractions (4 Hz, 52.0 ± 4.8 vs. 43.0 ± 3.6%; 8 Hz, 51.0 ± 4.6 vs. 41.0 ± 3.6%). Therefore, an excess in oxygen delivery occurs relative to oxygen use during muscle contractions in SHR. The previous and current results can be reconciled by considering the possibility that oxygen exchange is limited in SHR by a decrease in anatomic or perfused capillary density, arteriovenular shunting of blood, or decreased transit time of red blood cells through exchange vessels.

Original languageEnglish (US)
Pages (from-to)101-111
Number of pages11
JournalJournal of Applied Physiology
Volume78
Issue number1
DOIs
StatePublished - 1995

Keywords

  • exercise
  • feed arteries
  • functional vasodilation
  • hemoglobin oxygen saturation
  • recovery blood flow
  • recovery times
  • skeletal muscle blood flow

ASJC Scopus subject areas

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

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