Cimaterol reduces beta-adrenergic receptor density in rat skeletal muscles.

Abstract

Interactions between the beta-adrenoceptor agonist cimaterol and beta-adrenoceptors on rat skeletal muscle membranes were examined in two studies. In Exp. 1, muscle samples from eight Sprague-Dawley rats (female, approximately 200 g) were used for competition binding and autoradiographic studies using [125I]cyanopindolol (ICYP) as a radioligand. The affinities or dissociation constants for binding (KD values) for cimaterol in plantaris and soleus muscles were .68 and .92 microM, respectively. Muscle areas stained for succinic dehydrogenase had propranolol-resistant ICYP binding sites; cimaterol did not seem to compete for these sites. In Exp. 2, 60 Sprague-Dawley rats (female, approximately 218 g) were fed 0 or 10 ppm of cimaterol in rat diet that was ground. Groups were killed after 1, 3, 7, 14, or 28 d of treatment. Cimaterol increased BW gain up to 14 d after commencement of treatment, with little or no improvement thereafter. Enhanced weight gain in skeletal muscles also occurred up to 14 d of cimaterol treatment. Densities of beta-adrenoceptors in plantaris and soleus muscle membrane homogenates were estimated using a radioligand binding assay with ICYP. A significant reduction in the number of binding sites (Bmax) was observed after 3 d of cimaterol treatment in plantaris muscle without a change in the KD of ICYP binding. The percentage reductions in Bmax were 26.8, 42.2, 37.7, and 37.8% at 3, 7, 14, and 28 d after cimaterol administration, respectively. In the soleus muscle, significant reductions (44.1 and 29.8%) in Bmax were observed after 3 and 14 d of cimaterol treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

• Authors: Y S Kim, R D Sainz, R J Summers, P Molenaar
• Journal: Journal of animal science (J Anim Sci) Vol. 70 Issue 1 Pg. 115-22 (Jan 1992) ISSN: 0021-8812 [Print] United States
• PMID: 1374751 (Publication Type: Journal Article)

Chemical References

• Adrenergic beta-Agonists
• Ethanolamines
• Ligands
• Receptors, Adrenergic, beta
• Succinate Dehydrogenase
• cimaterol

Topics

• Adrenergic beta-Agonists (metabolism, pharmacology)
• Animals
• Autoradiography
• Binding, Competitive
• Ethanolamines (metabolism, pharmacology)
• Female
• Ligands
• Muscles (drug effects, metabolism)
• Rats
• Rats, Inbred Strains
• Receptors, Adrenergic, beta (drug effects, metabolism)
• Staining and Labeling
• Succinate Dehydrogenase
• Weight Gain (drug effects)