Production
The ANP-gene has 3 exons and 2 introns, it codes 151 aminoacid preproANP. Cleaving the 25 N-terminal results in pro-ANP. Corin a membrane serinprotease cleaves hereof the final ANP,the 28 aminoacid C-terminal. ANP is produced, stored and released mainly by cardiac myocytes of the atria of the heart. In a more less extend synthesis of ANP will also take place in the heartventricles, brain, suprarenal gland and renal gland. It is released in response to atrial stretch and a variety of other signals induced by hypervolemia, exercise or caloric restriction. The hormone is constitutively expressed in the ventricle in response to stress induced by increased afterload (e.g. increased ventricular pressure from aortic stenosis) or injury (e.g. myocardial infarction).
ANP is secreted in response to:
- Atrial distention, stretching of the vessel walls
- Sympathetic stimulation of β-adrenoceptors
- Raised sodium concentration (hypernatremia), though sodium concentration is not the direct stimulus for increased ANP secretion
- Angiotensin-II
- Endothelin, a potent vasoconstrictor
The atria become distended by high extracellular fluid and blood volume, and atrial fibrillation. Notably, ANP secretion increases in response to immersion of the body in water, which causes atrial stretch due to an altered distribution of intravascular fluid. ANP secretion in response to exercise has also been demonstrated in horses.
Read more about this topic: Atrial Natriuretic Peptide
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