Display options
Share it on
Full text links
Wiley Free PMC Article

Br J Pharmacol. 1990 Aug;100(4):767-73. doi: 10.1111/j.1476-5381.1990.tb14090.x.

The influence of the initial stretch and the agonist-induced tone on the effect of basal and stimulated release of EDRF.

British journal of pharmacology

I A Dainty, J C McGrath, M Spedding, A G Templeton

Affiliations

  1. Institute of Physiology, University of Glasgow.

PMID: 2207498 PMCID: PMC1917605 DOI: 10.1111/j.1476-5381.1990.tb14090.x
Free PMC Article

Abstract

1. The effects of initial stretch and degree of agonist-induced tone on acetylcholine-induced relaxations were examined in rings of rat isolated aorta. The relaxation to acetylcholine was antagonized by atropine and almost completely abolished by haemoglobin. Relaxation to sodium nitroprusside was similar in rings with an intact or disrupted endothelium but that to isoprenaline was greater in intact preparations. 2. In preparations with either an intact or disrupted endothelium there was a similar length-dependent increase in the resting tension of the aortic rings. The size of the contractile response to phenylephrine (1 microM) was dependent on the initial length (and hence degree of stretch) of the preparation in both rubbed and unrubbed tissues. The absolute difference in contractile response between rubbed and unrubbed was greatest at 1.8 mm and less at the other lengths tested, including the optimum degree of stretch for contraction i.e. 2.4 mm. 3. The absolute acetylcholine-induced relaxation (only seen in rings with an intact endothelium) was dependent on the initial length (and hence degree of stretch) of the preparation and was maximum at 2.4 mm. The proportionate relaxation (i.e. expressed as a percentage of induced tone) was also length-dependent being optimal at 1.5 mm. 4. The sensitivity of the vessels to acetylcholine varied depending on the level of agonist-induced tone. When tone was low, acetylcholine sensitivity was high (at [NA] 0.03 microM: pIC50 = 7.36 +/- 0.07), when the concentration of noradrenaline was increased the tone increased and the acetylcholine sensitivity was low (at [NA] 0.3 microM: pIC50 = 6.57 +/- 0.07). 5. The absolute sensitivities and maximum relaxations induced by acetylcholine are discussed in relation to the initial degree of stretch (and hence length of the preparation) or the degree of agonist-induced tone.

Cited by

References

  1. Circ Res. 1977 Jul;41(1):19-26 - PubMed
  2. Nature. 1980 Nov 27;288(5789):373-6 - PubMed
  3. Circ Res. 1983 Nov;53(5):557-73 - PubMed
  4. Acta Physiol Scand. 1985 Nov;125(3):429-35 - PubMed
  5. J Pharmacol Exp Ther. 1986 May;237(2):529-38 - PubMed
  6. Br J Pharmacol. 1986 Aug;88(4):767-77 - PubMed
  7. Br J Pharmacol. 1986 Dec;89(4):819-30 - PubMed
  8. J Cardiovasc Pharmacol. 1986 Nov-Dec;8(6):1158-62 - PubMed
  9. Nature. 1987 Jun 11-17;327(6122):459-60 - PubMed
  10. Nature. 1987 Jun 11-17;327(6122):524-6 - PubMed
  11. Naunyn Schmiedebergs Arch Pharmacol. 1988 May;337(5):525-30 - PubMed
  12. Br J Pharmacol. 1989 Jun;97(2):563-71 - PubMed

Substances

MeSH terms

Publication Types

LinkOut - more resources