Effect of bilateral adrenalectomy on catecholamine synthesis in the rat heart

ABSTRACT

The present study was carried out to investigate the possibility of local epinephrine [E] synthesis in rat cardiac tissue and to study the effect of bilateral adrenalectomy [A DX] on catecholamine synthesis. Bilateral adrenalectomy caused significant reductions of cardiac and plasma E levels but a substantial amount of E [33.3 percent] was retained in the atrium 9 days after bilateral adrenalectomy. Also, there was significant reductions in atrial norepinephrine [NE] and dopamine [DA] as well as ventricular DA. Cardiac epinephrine forming activity [EFA] was not significantly affected in ADX rats but ventricular EFA showed 42.3 percent increase compared to sham operated [SH] rats. Cardiac dopamine-B-hydroxyls [DBH] activity was increased in the atrium [31 percent] and in the ventricle [60 percent, p <0.01] of ADX rats compared to SH rats. In SH rats, decapitation increased plasma E by 61 fold but lowered plasma DA levels significantly compared to the corresponding rest values indicating that plasma DA is incorporated in the synthesis of catecholamines in the adrenal medulla. It was concluded that cardiac tissue synthesizes its own E and bilateral adrenalectomy increase the sympathetic activity, catecholamine synthesis and NE turnover