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Discussion Starter · #1 ·
A 60-year-old male is treated with losartan for hypertension. His blood pressure decreases to normal value over several weeks of treatment. He seems to be compliant with his medication and experiences no significant side effects. Which of the following is the most likely combination of changes in response to this patients treatment?


........Renin ....Angiotensin I ....Angiotensin II ....Aldosterone ....Bradykinin
A. Increase ....Increase .........Decrease ...........Increase .........Increase
B. Increase ....Increase .........Increase ............Decrease .........Increase
C. Increase ....Increase .........Increase ............Decrease .........No change
D. Increase ....Increase .........Decrease ...........Increase .........Decrease
E. Increase ....Decrease ........Decrease ...........Decrease .........Decrease
F. Decrease ...Decrease ........Decrease ...........Increase .........No change
 

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Discussion Starter · #8 ·
C) Increase-Increase-Increase-Decrease-No change

I'm impressed!!! all of you are correct

Correct ans is C) Increase-Increase-Increase-Decrease-No change

The renin-angiotensin-aldosterone system (RAAS) is one of the most important neurohormonal systems that regulate arterial blood pressure and sodium and fluid content in the body. In response to decreased sodium, fluid volume, or arterial blood pressure, renin is released from the kidneys converting angiotensinogen to angiotensin I. Subsequently, angiotensin converting enzyme (ACE) converts angiotensin Ito angiotensin II and is also responsible for the breakdown of bradykinin.

Angiotensin II stimulates angiotensin-1 receptors (AT-1) throughout the body constricting vascular smooth muscle and increasing aldosterone secretion from the adrenal cortex. AT-1 receptors are also involved in a negative feedback mechanism regulating the RAAS. Stimulation of AT-1 receptors on juxtaglomerular cells will decrease renin release from the kidneys, consequently decreasing angiotensin I and II levels.

Angiotensin receptor blockers like losartan (ARB5) competitively bind to AT-i receptors and block the effects of angiotensin II. This will result in vascular smooth muscle relaxation and decreased aldosterone secretion. Since ARBs directly block AT-i receptors, they do not affect ACE activity and should not affect bradykinin degradation or levels.
 
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