Effects of Chronic Administration of Carteolol on .BETA.-Adrenoceptors in Spontaneously Hypertensive Rat Heart.

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We studied the effects of chronic administration of β-adrenoceptor antagonists with and without intrinsic sympathomimetic activity (ISA): carteolol (with ISA) and propranolol (without ISA), respectively, on the heart of spontaneously hypertensive rat (SHR) and Wistar Kyoto rat (WKY). Six-week-old SHRs and WKYs were orally given carteolol or propranolol for ten weeks. The heart rate was reduced in propranolol-treated SHR, but not in carteolol-treated ones. In WKY, carteolol-treatment increased the heart rate. The number and affinities of β-adrenoceptors were analyzed using [<SUP>3</SUP>H]dihydroalprenolol as a ligand. Propranolol at 30 mg/kg increased the number of cardiac β-adrenoceptors in both SHR and WKY. In contrast, 10 mg/kg carteolol significantly decreased the number of cardiac β-adrenoceptors in SHR, but not in WKY. These data indicate that carteolol, a β-adrenoceptor antagonist with ISA, does not cause up-regulation of the number of cardiac β-adrenoceptors in the rat and suggest that this fact is related to a possible lack of "rebound phenomena" after sudden discontinuation of chronic carteolol-therapy in humans.
公益社団法人日本薬理学会の論文