Takayoshi Ikegaya

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This study was undertaken to examine the effects of hydrogen peroxide on stimulatory guanine nucleotide-binding protein (Gs), and coupling in the beta-adrenergic receptor-Gs-adenylate cyclase system in rat heart, in vitro. Cardiac membranes were preincubated with various concentrations (0.1, 1, and 10 mM) of hydrogen peroxide at 30 degrees C for 5, 10, 30(More)
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(More)
The Bio 14.6 cardiomyopathic Syrian hamster is an animal model of human idiopathic cardiomyopathy. The pathogenesis of the disease in this animal has not yet been clearly elucidated. It is well known that α- and β-adrenergic receptors are increased in the myocardium of this animal, but that isoprenaline does not produce an augmented response. We examined(More)
Purified porcine atrial muscarinic acetylcholine receptors were reconstituted into lipid vesicles with three different G proteins (Gi, Go and Gn)1 purified from porcine cerebrum. All the G proteins interacted with the receptor as evidenced by GTP-sensitive high affinity binding with acetylcholine, and stimulation by acetylcholine of GTP gamma S binding and(More)
We developed a simple procedure to detect the interaction of muscarinic receptors in atrial membranes with exogenous GTP-binding proteins (G proteins). The procedure consists of mixing atrial membranes with G proteins in the presence of sodium cholate, diluting the mixture with a salt buffer and then measuring the ligand binding activity. The displacement(More)
In general, it is recognized that prolonged exposure to catecholamine leads to a reduction in the β-adrenoceptor density (downregulation). However, it has been previously reported that the myocardial β-adrenoceptor densities and norepinephrine levels significantly increase in the hearts of BIO 14.6 cardiomyopathic hamsters in the early stage. The mechanism(More)
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