Blood pressure, the driving force that supplies nutrients and oxygen to all of your vital organs and tissues, is regulated by a plethora of physical and chemical factors. Hormones, neurotransmitters and electrolytes play critical roles in controlling your blood pressure, as do specialized receptors within the walls of your arteries. Dopamine, a neurotransmitter that is produced in the brain, adrenal glands and other tissues, participates in blood pressure regulation via its effects on the heart, kidneys, central nervous system and blood vessels.
Blood Pressure at a Glance
Your heart rate and the force of each heartbeat are mechanical parameters that can be used to estimate your blood pressure. Like any pump, the faster your heart runs and the more volume it pushes, the higher the pressure will be. However, unlike a mechanical pump, your heart pushes blood into “pipes” whose elasticity changes from moment to moment, and it receives continuous messages from the brain, the kidneys and other organs that alter its output with nearly every beat.
Dopamine Receptors Are the Key
Cellular receptors that respond to dopamine are present in a variety of tissues, including your arteries, veins, kidneys and heart. At least five different dopamine receptors have been identified, and, according to a 2003 review in “Nephron Physiology,” every one of these receptor types plays a role in blood pressure regulation. The nature of the blood pressure response depends on which receptors are stimulated or, conversely, inhibited.
Dopamine and Hormones
The renin-angiotensin system, or RAS, is a metabolic pathway that ultimately leads to the production of hormones that are intimately involved in blood pressure regulation. One of these hormones, angiotensin II, causes blood vessels to constrict, which raises blood pressure. Angiotensin II stimulates the release of another hormone, aldosterone, which signals the kidneys to retain sodium and water. This, too, leads to an increase in blood pressure. The RAS is triggered when dopamine receptors in the kidneys are stimulated. Dopamine’s influence on other hormones, such as prolactin, can also lead to increases in blood pressure.
Dopamine and Electrolytes
Dopamine’s activation of the RAS is not the sole means by which this neurotransmitter influences electrolyte levels. In the April 2000 issue of “Current Hypertension Reports,” scientists noted that dopamine acts directly on the gut, the brain and the kidneys to increase sodium intake, absorption and retention and thereby increases blood pressure. These investigators state that a derangement of dopamine receptor regulation may play a role in the development of high blood pressure in humans.
Dopamine is a precursor to other catecholamine neurotransmitters, namely norepinephrine and epinephrine, or adrenalin. Catecholamines are generally “excitatory” in nature, meaning they increase your heart rate and cause your blood vessels to constrict, both of which lead to a rise in blood pressure.
Dopamine's Central Role
Dopamine plays a central role in the complex processes that control your blood pressure. Dopamine’s actions on your heart, blood vessels, brain and kidneys trigger physiologic responses that increase sodium and water retention, increase your heart rate and constrict your blood vessels. In concert, these actions generate higher pressures. Aberrations in dopamine receptor activity or regulation, some of which are genetically determined, probably contribute to hypertension, or high blood pressure.