Evidence for increased and insulin-resistant lipolysis in skeletal muscle of high-fat-fed rats

ZengKui Guo, Lianzhen Zhou

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

The metabolic and isotopic profiles of glycerol in skeletal muscle were examined using awake, fasted lean and high-fat-induced obese rats, and hyperinsulinemic-euglycemic clamp was performed to assess the effect of insulin. During the clamp, Intralipid (no heparin; Fresnius Kabi Clayton, Clayton, NC), free fatty acids, glycerol, and glucose were coinfused to maintain their respective basal plasma levels in both groups. At steady-state, [U- 14C]glycerol was infused intravenously for 120 minutes followed by muscle biopsy. The classical phenotypic characteristics of obesity, namely, reduced insulin-stimulated glucose uptake, a failure to suppress systemic lipolysis by insulin, and elevated plasma fatty acid concentration, were observed in the obese rats. Novel observations showed that in the basal state, the isotopic specific activity (S.A.) of glycerol (dpm/nmol) in gastrocnemius (0.03 v 0.12), soleus (0.05 v 0.12), and tibialis anterior (0.03 v 0.12) was significantly lower (all P < .003) in obese than in lean rats despite similar concentrations, indicating an active basal intramyocellular lipolysis. In addition, the lipolysis appeared resistant to insulin because the suppression of muscle glycerol during the clamp was 8%, 12%, and 8% in obese compared to 67%, 71%, and 63% in the lean control for gastrocnemius (P = .001), soleus (P = .007), and tibialis anterior (P = .004), respectively. The active intracellular lipolysis likely disturbs metabolic functions that may contribute to insulin resistance.

Original languageEnglish (US)
Pages (from-to)794-798
Number of pages5
JournalMetabolism: Clinical and Experimental
Volume53
Issue number6
DOIs
StatePublished - Jun 2004

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Lipolysis
Glycerol
Skeletal Muscle
Fats
Insulin
Glucose
Muscles
Glucose Clamp Technique
Metabolome
Nonesterified Fatty Acids
Insulin Resistance
Heparin
Fatty Acids
Obesity
Biopsy

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Evidence for increased and insulin-resistant lipolysis in skeletal muscle of high-fat-fed rats. / Guo, ZengKui; Zhou, Lianzhen.

In: Metabolism: Clinical and Experimental, Vol. 53, No. 6, 06.2004, p. 794-798.

Research output: Contribution to journalArticle

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