T Okamoto-Koizumi

Niigata University, Niahi-niigata, Niigata, Japan

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Publications (1)4.86 Total impact

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    ABSTRACT: The aim of this study was to characterize endothelin receptor subtypes of the detrusor muscle of the human urinary bladder. The receptor subtypes mediating endothelin (ET)-1-induced activity in the human detrusor smooth muscles have been characterized using isometric contraction and reverse transcription-polymerase chain reaction (RT-PCR). ET-1 (a non-selective ET receptor agonist; 10(-10) M to 10(-6) M) exhibited concentration-dependent contractions in human urinary bladder with a plateau at concentrations above 3x10(-7) M. Neither IRL1620 nor sarafotoxin S6c (both ETB-selective agonists; 10(-10) M to 10(-6) M) elicited contractile activity in the human urinary bladder detrusor smooth muscle. FR139317 (an ETA-selective antagonist; 10(-7) M to 10(-5) M) produced a marked shift to the right of the ET-1 concentration-response curve in human urinary bladder detrusor smooth muscle (from the Schild plot TpA2=7.96; slope=0.95). In contrast, RES701-1 (an ETB-selective antagonist; 10(-7) M to 10(-5) M) had no effect on the ET-1 concentration-response curve. RT-PCR revealed positive amplification of ETA receptor mRNA fragment, but not ETB. These results indicate that the ET-1-induced contractile effects of urinary bladder detrusor smooth muscle seem to be mediated mainly by the ETA receptor, not by the ETB receptor.
    Clinical Science 05/1999; 96(4):397-402. · 4.86 Impact Factor