Abstract
Abstract
Adrenalectomized, medullectomized and sham operated rats were treated with either a chronic infusion or a bolus injection of the synthetic atrial natriuretic factor (ANF). ANF did not enhance natriuresis and diuresis in sham operated conscious animals during chronic infusion, but it had a potent action when injected as a bolus into anesthetized rats. The absence of the whole adrenal glands, but not adrenal medulla profoundly modified the renal response to ANF: a) following chronic administration of ANF, the baseline natriuresis paradoxically decreased in adrenalectomized rats, and b) in response to a bolus injection of ANF the natriuretic and diuretic actions of the peptide were attenuated in these animals. The medullectomy-induced decreased natriuresis and dopamine excretion were corrected by ANF infusion. Furthermore, ANF suppressed the compensatory increase of norepinephrine excretion secondary to adrenalectomy. The data suggest that the presence of the adrenal cortex is necessary for the natriuretic and diuretic actions of ANF. The decrease in urinary DA excretion may reflect diminished dopaminergic activity and contribute to the post-medullectomy antinatriu-resis, a phenomenon which can be corrected by ANF infusion. ANF may also have a depressing activity on the increased sympathetic tone.
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