Skeletal muscle blood flow in vivo: detection with rubidium-82 and effects of glucose, insulin, and exercise
In order to assess the effects of glucose, insulin, and exercise on skeletal muscle blood flow in vivo, we measured positron emission from the thigh muscle of anesthetized rabbits after simultaneous aortic bolus injection of /sup 82/Rb and radiolabeled microspheres (15 micron diameter). Estimates of flow with /sup 82/Rb were based on first-pass regional extraction of /sup 82/Rb by skeletal muscle. Flow estimates were made serially as a function of variations in plasma glucose and insulin and changing the muscle contractile state by electrical stimulation. Flow ranged from 3.1 ml/min/100 g at rest to 71 ml/min/100 g during stimulation. There was good agreement between the two methods of flow measurement over the entire range of flows (r = 0.96 at a slope of 0.90). Flow measured by either method did not vary significantly from baseline over a range of plasma glucose from 5 to 30 mM and plasma insulin from 0 to 20 microU/ml. When flow was increased up to 20-fold by electrical stimulation there was a decrease in extraction of /sup 82/Rb proportional to the increase in flow. However, at pharmacologic levels of insulin (greater than 150 microU/ml) flow was increased twofold as measured by radiolabeled microspheres, but not as measured by rubidium. There was no apparent decrease in extraction of /sup 82/Rb with high insulin. The discrepancy between the microsphere measured flow and rubidium measured flow with high plasma insulin levels can be explained by the assumption that the expected decrease in the extraction fraction was counteracted by an increase in Na+/K+-ATPase activity. It is concluded that the first-pass flow model gives valid estimates of skeletal muscle blood flow in vivo with /sup 82/Rb, provided that plasma insulin levels are normal.
- Research Organization:
- Univ. of Texas Medical School, Houston
- OSTI ID:
- 6215660
- Journal Information:
- J. Nucl. Med.; (United States), Vol. 28:7
- Country of Publication:
- United States
- Language:
- English
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EXERCISE
BIOLOGICAL EFFECTS
GLUCOSE
INSULIN
MUSCLES
BLOOD FLOW
DYNAMIC FUNCTION STUDIES
MICROSPHERES
POSITRON COMPUTED TOMOGRAPHY
RABBITS
RUBIDIUM 82
ALDEHYDES
ALKALI METAL ISOTOPES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
CARBOHYDRATES
COMPUTERIZED TOMOGRAPHY
DIAGNOSTIC TECHNIQUES
ELECTRON CAPTURE RADIOISOTOPES
EMISSION COMPUTED TOMOGRAPHY
HEXOSES
HORMONES
HOURS LIVING RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
ISOTOPES
MAMMALS
MINUTES LIVING RADIOISOTOPES
MONOSACCHARIDES
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PEPTIDE HORMONES
RADIOISOTOPES
RUBIDIUM ISOTOPES
SACCHARIDES
TOMOGRAPHY
VERTEBRATES
550601* - Medicine- Unsealed Radionuclides in Diagnostics