Incubation of rat aortic rings produces a specific reduction in agonist-evoked contraction: effect of age of donor

Life Sci. 2004 Nov 19;76(1):9-20. doi: 10.1016/j.lfs.2004.04.058.

Abstract

We studied the effect of age on the response of aortic rings to injury produced by three days' incubation, and the mechanism of this response. Five-mm rings of the thoracic aorta isolated from Wistar rats were incubated or not in culture medium. Isometric contraction evoked by agonists (norepinephrine or serotonin) or high [K(+)](e) was determined in the presence and absence of endothelium. Experiments were repeated in the presence of propranolol (0.3 microM), polymixin B (36 microM), pyrrolidine dithiocarbamate (50 microM) or glutathione (3 mM). Inductible NO-synthase and cyclo-oxygenase-2 mRNA were determined by real-time PCR, and glutathione-related enzymes and catalase activity by spectrophotometry. Incubation reduced the isometric contraction evoked by agonists but not by high [K(+)](e). The reduction in agonist-evoked contraction was greater in rings from adult (norepinephrine Emax-80%) than in young (-40%) rats. The removal of the endothelium had no effect. The reduction in norepinephrine-evoked contraction was not due to endotoxin contamination, beta-adrenoceptor-mediated dilation or any change in ring structure (no fibrosis or edema). Inductible NO-synthase (but not cyclo-oxygenase-2) mRNA increased on incubation. N(G)-nitro-L-arginine methyl ester partially restored contractility in rings from adult animals, further addition of an anti-oxidant restored norepinephrine-evoked contraction. Catalase fell with age and glutathione reductase increased upon incubation in rings from young donors only. In conclusion, incubation of the aorta produces a specific reduction in agonist-evoked contraction that involves induction of smooth muscle cell oxidative stress and iNOS. The reaction is greater in rings from older animals.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Analysis of Variance
  • Animals
  • Aorta, Thoracic / physiology*
  • Catalase / metabolism
  • Culture Media / pharmacology*
  • Cyclooxygenase 2
  • DNA Primers
  • Glutathione / pharmacology
  • Isoenzymes / genetics
  • Isoenzymes / metabolism
  • Male
  • Muscle Contraction / drug effects*
  • Muscle Contraction / physiology
  • Muscle, Smooth, Vascular / drug effects*
  • Muscle, Smooth, Vascular / physiology
  • Nitric Oxide Synthase / genetics
  • Nitric Oxide Synthase / metabolism
  • Nitric Oxide Synthase Type II
  • Norepinephrine / pharmacology
  • Potassium / pharmacology
  • Propranolol / pharmacology
  • Prostaglandin-Endoperoxide Synthases / genetics
  • Prostaglandin-Endoperoxide Synthases / metabolism
  • Pyrrolidines / pharmacology
  • RNA, Messenger / metabolism*
  • Rats
  • Rats, Wistar
  • Reverse Transcriptase Polymerase Chain Reaction
  • Serotonin / pharmacology
  • Spectrophotometry
  • Thiocarbamates / pharmacology
  • Time Factors

Substances

  • Culture Media
  • DNA Primers
  • Isoenzymes
  • Pyrrolidines
  • RNA, Messenger
  • Thiocarbamates
  • pyrrolidine dithiocarbamic acid
  • Serotonin
  • Propranolol
  • Catalase
  • Nitric Oxide Synthase
  • Nitric Oxide Synthase Type II
  • Nos2 protein, rat
  • Cyclooxygenase 2
  • Prostaglandin-Endoperoxide Synthases
  • Glutathione
  • Potassium
  • Norepinephrine