Regional blood flow in genetically-obese rats during nonshivering thermogenesis

S. J. Wickler, Barbara A Horwitz, J. S. Stern

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


Labelled microspheres were used to measure blood flow in obese Zucker rats (fa/fa) and their lean littermates prior to and during i.v. infusion of L-isoproterenol (a β-agonist and potent stimulator of nonshivering thermogenesis). The tissues and organs examined were kidneys, liver, white adipose tissue (mesenteric), heart, skeletal muscle, and brown fat (cervical and interscapular depots). Resting blood flows were, on the average, lower in the tissues from obese individuals, but were not statistically different from those in lean animals, except in the liver. Cardiac outputs did not differ in obese and lean animals either at rest (82.9 and 84.5 ml/min, respectively) or during infusion of isoproterenol (107.4 and 115.5 ml/min, respectively). Isoproterenol significantly decreased blood flow to kidney, liver, and white fat of both obese animals (33, 34 and 16 percent, respectively) and lean animals (25, 24 and 63 percent). Conversely, isoproterenol increased blood flow to cardiac tissue, skeletal muscle, and brown fat (average of cervical and interscapular depots) of both obese animals (40, 220, and 460 percent) and lean animals (94, 74 and 1935 percent). Tissue blood flow was used as an indicator of the potential contribution of the tissue to catecholamine-induced calorigenesis. The decreased blood flow to lean and obese liver, kidney, and white fat during isoproterenol infusion suggests that these tissues contribute little, at least directly, to the calorigenic response. The greatest differences in isoproterenol-stimulated blood flows between obese and lean rats were evident in brown fat. Blood flows per g of tissue were an order of magnitude lower in obese animals. Thus in obese rats there is a decreased capacity of brown fat to respond to catecholamines which appears to be reflected in a diminished calorigenic response. This interpretation agrees with that based on results from obese mice and suggests that the decreased thermogenic response of brown adipose tissue may indeed be an important factor in the manifestation of the animals' obesity.

Original languageEnglish (US)
Pages (from-to)481-490
Number of pages10
JournalInternational Journal of Obesity
Issue number5
StatePublished - 1982

ASJC Scopus subject areas

  • Food Science
  • Endocrinology
  • Medicine (miscellaneous)
  • Endocrinology, Diabetes and Metabolism
  • Public Health, Environmental and Occupational Health


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