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ACE inhibitors, ARBs and direct renin inhibitors
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Blood pressure is the force that blood exerts on the walls of blood vessels.
Now, there’s a number of factors that determine blood pressure. For example, imagine a hose connected to a pump where the hose is the blood vessel and the pump is the heart. If more water is pumped out, the pressure in the hose increases.
Now if we squeeze the hose, narrowing the diameter, the pressure inside would be greater and the water will shoot out more strongly. This is similar to how the diameter of the blood vessels can affect blood pressure, which can change in response to different stimuli.
Renin is a proteolytic enzyme that breaks down a protein made in the liver called angiotensinogen, and this gives rise to angiotensin I.
When it reaches the lungs, angiotensin I is converted into angiotensin II by an enzyme called Angiotensin-converting enzyme, or ACE for short.
Now, angio- refers to the blood vessels; and -tens, well it means “to tense.”
So angiotensin II binds to receptors in vascular smooth muscle and causes them to constrict, which increases the blood pressure.
Finally, angiotensin II also stimulates the release of aldosterone by the adrenal glands.
ACE inhibitors, ARBs and direct renin inhibitors are all medications used to treat high blood pressure. ACE or angiotensin-converting enzyme inhibitors work by blocking the enzyme that converts angiotensin I to angiotensin II. This prevents the body from producing too much of the hormone, which can lead to hypertension. ARBs or angiotensin II receptor blockers work by blocking the receptors that angiotensin II binds to constrict blood vessels. This relaxes the blood vessels and lowers blood pressure. Direct renin inhibitors work by inhibiting renin, the enzyme that converts angiotensinogen to angiotensin I, which also reduces blood pressure. All three of these medications can be used alone or in combination with other medications to safely lower blood pressure.
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