Receptor Binding Sites of Atrial Natriuretic Factor in Bovine Brain Microvessels

Atrial natriuretic factors (ANFs) have been isolated from secretory like granules present in the myocytes of mammalian atria. These peptides modulate blood pressure homeostasis, aldosterone production and extracellular fluid volume by acting as a circulating hormone (1,2). They possess potent vasorelaxant properties which are associated with ANFs binding to specific receptors in vascular tissues (3,4). Moreover, they counteract in many respects the action of Ang II. On the basis of evidence that ANF acts directly on vascular endothelium and since Ang II binding sites have been recently described in brain microvessels (5), we hypothetized that ANF receptors can also be present in brain microvessels. To test this hypothesis, radioreceptor binding of 125I-labeled ANF (125I-ANF) on pure and homogenous preparation of bovine brain microvessels was used.