Cardiac chamber-specific β-adrenoceptor regulation and sympathetic innervation

We assessed by radioligand binding techniques the effect of cardiac failure on β-adrenoceptor density in 5 hearts from patients undergoing repeat transplantation and 5 normal (unused donor) hearts. Right ventricular total and subtype β-adrenoceptors in the denervated repeat- transplant hearts were down-regulated compared with the normally innervated controls. Within the denervated hearts, β1-adrenoceptors were selectively down-regulated in the right ventricle compared with the left ventricle. Tissue noradrenaline content confirmed sympathetic denervation in the transplanted hearts. Thus, regional sympathetic innervation is not necessary for chamber-specific β-adrenoceptor down-regulation; other mechanisms for this process should be sought.