The role of ANF in functional properties of the central pathways of cardiovascular reflexes

Abstract

A number of peptide hormones first identified for their peripheral actions are found within the brain where they may subserve a transmitter or modulator role. Atrial natriuretic factor (ANF), a peptide capable of inducing peripheral natriuretic, diuretic and hypotensive effects, has been recently proposed to play a role in central cardiovascular regulation [6]. Binding sites for ANF as well as ANF-containing cell bodies and fibres have been identified in many brain areas, most notably in areas implicated in cardiovascular control [5]. In addition it has been shown that (i) ANF is synthesized and stored by neurons [6]; (ii) ANF can alter the activity of neurons [2,3]; (iii) ANF, if microinjected into discrete sites of the nucleus tractus solitarii (NTS), particularly in areas near the obex, where central projections of arterial baroreceptors terminate within the NTS, can elicit arterial hypotension [4]. We first studied the effect on neuronal firing rate, arterial pressure (AP) and heart rate (HR) of microinjections of ANF on single NTS neurons in anesthetized rats, to evaluate whether neuronal responses to ANF were related to AP and HR changes and whether or not NTS neurons affected by ANF receive a baroreceptor input.