Role of alpha 1-adrenergic receptors and the effect of bunazosin on the histopathology of cardiomyopathic Syrian hamsters of strain BIO 14.6

• Published in: Japanese circulation journal Vol. 52; no. 2; pp. 181 - 187
• Main Authors: Ikegaya, T, Nishiyama, T, Kobayashi, A, Yamazaki, N
• Format: Journal Article
• Language: English
• Published: Japan 01.02.1988
• Subjects: Adrenergic alpha-Antagonists - pharmacology; Animals; Cardiomyopathies - metabolism; Cardiomyopathies - pathology; Cricetinae; Female; Male; Mesocricetus; Myocardium - metabolism; Quinazolines - pharmacology; Receptors, Adrenergic, alpha - metabolism; Receptors, Adrenergic, beta - metabolism
• ISSN: 0047-1828
• DOI: 10.1253/jcj.52.181

In order to clarify the pathological involvement of the sympathetic nervous system in the development of cardiomyopathy, a receptor-binding study was carried out on cardiomyopathic Syrian hamsters of strain BIO 14.6 (BIO) at 21 days (prenecrotic stage); 35-42 days (onset of cardiomyopathy); and 70-84 days of life (early cardiac hypertrophy). The newly developed alpha 1-blocker (bunazosin hydrochloride) was initially administered at doses of 100 micrograms/kg or 10 mg/kg to BIO hamsters at 21 days of life and continued for 70 days. At the onset of cardiomyopathy and early cardiac hypertrophy, there was an increase in the number of alpha 1-receptors in the BIO hamsters compared to controls, but there were no significant changes at the prenecrotic stage. On histopathological examination, 10 mg/kg bunazosin had a significant beneficial effect on cardiomyopathy [area of necrosis 1.38% in untreated vs 0.33% in treated animals; area of calcification 2.70% (untreated) vs 0.60% (treated); area of all myocardial injuries 6.97% (untreated) vs 3.19% (treated)]. However, 100 micrograms/kg bunazosin had no effect. It was concluded that the increase in the number of alpha 1-receptors may not be involved in the pathogenesis of cardiomyopathy but that alpha 1-receptors could be implicated in the later progression of the condition.