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Physiology of natriuretic peptides: The volume overload hypothesis revisited
1Olli Arjamaa, Department of Biology, University of Turku, 20014 Turku, Finland.
Insights
The heart acts as an endocrine organ, releasing natriuretic peptides that regulate blood circulation and blood pressure. These peptides may also play a role in oxygen transport during volume contraction.
Area of Science:
- Cardiology
- Endocrinology
- Physiology
Background:
- The discovery of the natriuretic peptide system revealed the heart's endocrine function beyond its mechanical role.
- Natriuretic peptides are released in response to cardiac volume overload, influencing natriuresis and diuresis.
- These peptides exhibit effects similar to antihypertensive drugs, impacting blood circulation.
Purpose of the Study:
- To present a hypothesis on the role of natriuretic peptides in regulating oxygen transport.
- To explore the connection between volume contraction, hemoconcentration, and oxygen-carrying capacity.
- To investigate the influence of myocardial wall stress on oxygen diffusion within myocytes.
Main Methods:
- Review of existing literature on natriuretic peptides and cardiac function.
- Hypothetical model development linking natriuretic peptides to oxygen transport regulation.
- Analysis of genetic evidence, specifically hypoxia-response elements in natriuretic peptide genes.
Main Results:
- Natriuretic peptides are implicated in regulating oxygen transport during states of volume contraction.
- Volume contraction leads to hemoconcentration, enhancing the blood's oxygen-carrying capacity.
- Myocardial wall stress (chemical or mechanical) affects the myocardial oxygen gradient and intracellular oxygen diffusion.
Conclusions:
- Natriuretic peptides play a crucial role in cardiovascular homeostasis and oxygen transport regulation.
- The heart's endocrine function is vital for adapting to changes in blood volume and oxygen demand.
- Genetic evidence supports the involvement of natriuretic peptides in cellular responses to hypoxia.
Abstract:
The discovery of the natriuretic peptide system in the early 1980s aroused great interest among clinical cardiologists. The heart was not a mechanical pump alone, but also an endocrine organ that had powerful effects on blood circulation. Natriuretic peptides caused both natriuresis and diuresis, and they responded to a volume overload which caused either stretch or pressure on the heart. As a result, the findings led to the conclusion that the human body had a hormone with effects similar to those of a drug which treats high blood pressure. Later, it became evident that the volume contraction was fortified by extrarenal plasma shift. Here, a hypothesis is presented in which the role of natriuretic peptides is to regulate oxygen transport as the volume contraction leads to hemoconcentration with an increased oxygen-carrying capacity. Wall stress, either chemical or mechanical, changes the oxygen gradient of the myocardium and affects the diffusion of oxygen within a myocyte. In support of this hypothesis, hypoxia-response elements have been found in both the atrial natriuretic peptide and the brain natriuretic peptide genes.
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