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).
|Number of pages||4|
|Journal||Clinical and Experimental Pharmacology and Physiology|
|Publication status||Published - 1 Jan 1993|
- ET receptor
- inositol phosphates
- neonatal cardio‐myocyte
- neonatal heart
- receptor cross‐linking.