Question

Scenario: DW is a 65-year-old, 135 kg male who visited his primary care physician for a routine examination. His blood pressure was 158/100 mmHg and his heart rate was 71 bpm. Stroke volume and cardiac output were normal. Serum renin levels were in the normal range.   A chest x-ray revealed left ventricular hypertrophy. Other clinical findings were unremarkable.

In the description of the case, serum renin is said to be in normal range. Elevated renin would indicate that vasoconstrictor hormone angiotensin II is elevated. Assume that this case indicated renin is elevated, and predict that angiotensin II would also be elevated. How would this hormone affect blood pressure (be specific).

Answer 1

RAAS is a system that regulate BP Via ccordinated action of different enzymes and hormones

renin level increased_increases conversion of angiotensin1 into angiotensin2 by ACE enzyme in lungs.

Angiotensin 2 causes acute rise in BP by vasoconstriction.Also long lasting effectd by directly as well as indirectly(aldosterone)increasing Na+and water reabsorption in the kidney(increased BP).

Rise in BP inturn inhibits renin release_the long loop negative feedback mechanism.It has been shown that angiotensin2 can be formed within the kidney and exerts important local regulatory effevts.A short loop negative feedback mechanism operates within the kidney;activation of AT1 receptors on JG cells inhibit renin reease directly.Longterm stabilization of BP despite varying salt and water intake appears to be achived through these mechanisms.