Beta-adrenoceptor agonist mediated relaxation of rat isolated resistance arteries: a role for the endothelium and nitric oxide

Br J Pharmacol. 1993 Mar;108(3):631-7. doi: 10.1111/j.1476-5381.1993.tb12853.x.

Abstract

1. Isoprenaline (10(-9)-10(-5) M) relaxed rat isolated mesenteric resistance arteries pre-contracted with K+ (30-60 mM) (p EC50 (M) 8.03 +/- 0.40; maximum relaxation 66.79 +/- 2.43%, n = 7). This relaxation was partially attenuated by the nitric oxide (NO) synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME, 10(-4) M). 2. The beta 2-adrenoceptor agonist, salbutamol (10(-9)-10(-5) M), produced a modest maximum relaxation (35.93 +/- 2.93%), which was not sensitive to L-NAME. 3. The beta 1-adrenoceptor agonist, dobutamine (10(-9)-10(-5) M), relaxed arteries precontracted with K+. This relaxation was abolished by L-NAME (10(-4) M) and also by propranolol (10(-6) M), but not affected by D-NAME (10(-4) M). The inhibition by L-NAME was partially reversed by L-arginine (10(-3) M). Removal of the endothelium severely attenuated relaxation to dobutamine. 4. Contractile responses to depolarizing K+ solutions were enhanced by the addition of L-NAME, and also by removal of the endothelium. 5. The above findings demonstrate that beta 1-adrenoceptor causes relaxation via NO release from the endothelium of rat mesenteric resistance arteries. In addition, contraction to K+ is modified by release of NO from the endothelium, possibly in response to tension development.

MeSH terms

  • Adrenergic beta-Agonists / pharmacology*
  • Albuterol / pharmacology
  • Animals
  • Arginine / analogs & derivatives
  • Arginine / pharmacology
  • Colforsin / pharmacology
  • Cyclic AMP / physiology
  • Dobutamine / pharmacology
  • Endothelium, Vascular / physiology*
  • In Vitro Techniques
  • Isoproterenol / pharmacology
  • Male
  • Mesenteric Arteries / drug effects
  • Muscle Relaxation / drug effects
  • Muscle, Smooth, Vascular / drug effects*
  • NG-Nitroarginine Methyl Ester
  • Nitric Oxide / pharmacology*
  • Potassium / pharmacology
  • Propranolol / pharmacology
  • Rats
  • Rats, Inbred WKY
  • Vascular Resistance / drug effects

Substances

  • Adrenergic beta-Agonists
  • Colforsin
  • Nitric Oxide
  • Dobutamine
  • Arginine
  • Propranolol
  • Cyclic AMP
  • Isoproterenol
  • Albuterol
  • Potassium
  • NG-Nitroarginine Methyl Ester