Angiotensin II enhances beta-adrenergic receptor-mediated vasorelaxation in aortas from young but not old rats

Am J Physiol Heart Circ Physiol. 2000 Dec;279(6):H2807-14. doi: 10.1152/ajpheart.2000.279.6.H2807.

Abstract

beta-Adrenergic receptor (beta-AR)-mediated (cAMP-dependent) vasorelaxation declines with advancing age. It has been shown that angiotensin II (ANG II), a potent vasoconstrictor, enhances cAMP-mediated vasorelaxation. Therefore, we questioned whether ANG II could reverse age-related, impaired beta-AR-mediated vasorelaxation and cAMP production. Pretreatment of aortic rings from 6-wk-old or 6-mo-old male Fischer 344 rats with ANG II significantly enhanced vasorelaxation induced by isoproterenol (Iso), a beta-AR agonist, and forskolin, a direct activator of adenylyl cyclase, but not dibutyryl-cAMP or isobutylmethylxanthine. The ANG II effect was blocked by losartan but not PD-123319 and was not observed in the aortas from 12- and 24-mo-old animals. Iso-stimulated cAMP production in the aorta was enhanced in the presence of ANG II in the 6-wk-old and 6-mo-old age groups only. Results suggest ANG II cannot reverse the age-related impairment in beta-AR-dependent vasorelaxation. We conclude aging may affect a factor common to both ANG II-receptors and beta-AR signaling pathways or aging may impair cross-talk between these two receptor pathways.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 1-Methyl-3-isobutylxanthine / pharmacology
  • Adrenergic beta-Agonists / pharmacology
  • Aging / physiology*
  • Angiotensin II / pharmacology*
  • Animals
  • Aorta, Thoracic / drug effects
  • Aorta, Thoracic / physiology*
  • Bucladesine / pharmacology
  • Colforsin / pharmacology
  • Cyclic AMP / metabolism
  • Imidazoles / pharmacology
  • In Vitro Techniques
  • Isoproterenol / pharmacology
  • Male
  • Phosphodiesterase Inhibitors / pharmacology
  • Pyridines / pharmacology
  • Rats
  • Rats, Inbred F344
  • Receptor Cross-Talk / drug effects
  • Receptor Cross-Talk / physiology
  • Receptor, Angiotensin, Type 1
  • Receptor, Angiotensin, Type 2
  • Receptors, Angiotensin / metabolism*
  • Vasoconstrictor Agents / pharmacology*
  • Vasodilation / drug effects
  • Vasodilation / physiology*

Substances

  • Adrenergic beta-Agonists
  • Imidazoles
  • Phosphodiesterase Inhibitors
  • Pyridines
  • Receptor, Angiotensin, Type 1
  • Receptor, Angiotensin, Type 2
  • Receptors, Angiotensin
  • Vasoconstrictor Agents
  • Angiotensin II
  • PD 123319
  • Colforsin
  • Bucladesine
  • Cyclic AMP
  • Isoproterenol
  • 1-Methyl-3-isobutylxanthine