(+)-Amosulalol ((+)-YM 09538) is an isomer of Amosulalol , an orally active dual inhibitor of α1/β1-adrenergic receptors. Amosulalol exhibits antihypertensive activity by inhibiting α1-adrenergic receptors. Amosulalol reduces the reflex increase in heart rate and plasma renin activity (PRA) in spontaneously hypertensive rats (SHR) by inhibiting β1-adrenergic receptors.