A LOW AFFINITY, LOW MOLECULAR WEIGHT ENDOTHELIN‐A RECEPTOR PRESENT IN NEONATAL RAT HEART

Elizabeth A. Woodcock, Sarah L. Land, Robert K. Andrews

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Abstract

1. Addition of endothelin‐1 (ET‐1) to [3H]‐inositol‐labelled neonatal rat hearts stimulated the accumulation of [3H]‐labelled inositol phosphates (InsP), but only at high concentrations; concentration at half maximum stimulation (EC50)>0.1 μmol/L). When similar experiments were performed using isolated myocytes, the potency of endothelin‐1 was higher and the EC50 value averaged 3.2 ± 0.5 nmol/L (mean±s.e.m., n = 4). 2. The binding affinity of [125I]‐endothelin‐1 was higher for receptors on isolated cells than for receptors on membranes prepared from intact heart (72 ± 16 pmol/L compared with 3.9 ± 0.7 nmol/L, mean ± s.e.m., n= 4, P < 0.01; Students’t test). 3. Receptors from both sources were cross‐linked to [125I]‐endothelin‐1 and their molecular weights measured using sodium dodecylsulfate gradient polyacrylamide gel electrophoresis (SDS‐PAGE). The receptors present on the isolated cells had a higher molecular weight (48 kD) than the receptor on the heart membranes (38 kD).

Original languageEnglish
Pages (from-to)331-334
Number of pages4
JournalClinical and Experimental Pharmacology and Physiology
Volume20
Issue number5
DOIs
Publication statusPublished - 1 Jan 1993
Externally publishedYes

Keywords

  • endothelin
  • endothelin‐1
  • endothelin‐3
  • ET receptor
  • inositol phosphates
  • neonatal cardio‐myocyte
  • neonatal heart
  • receptor cross‐linking.

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