Atrial natriuretic peptide negative-feedback loop?

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GT says that ANP exerts negative-feedback on the renin-angiotensin system.

To my understanding, a negative-feedback loop implies the inhibition of production/secretion of a moiety via the downstream effects of that moiety itself.

In other words, I would think that negative-feedback refers to the decreased production of a molecule not due to a moiety external to the production-cascade of that molecule.

With prolactin negative-feedback, for instance, increased prolactin leads to increased dopamine production, which in turn inhibits prolactin. There's no "external" molecule regulating that intrinsic loop, and in turn prolactin exerts negative-feedback on its own production.

With respect to ANP, however, I would think it's considered external to the renin-angiotensin loop because it's not actually produced in order to carry out the effects of that loop. So if ANP reduces activity of the renin-AT loop, that's not actually negative-feedback.


Any thoughts here / food for discussion?

Cheers,

Semantics. It's the end product of RAAS activation in the sense that it is produced in response to the increase in blood volume due to the combined effects of ATII and aldosterone, but I can see why you might say it's outside of the system. I personally don't like the boundary because it's an integrated system and it seems kind of arbitrary to me.