Question

1. Why would a drug called renin inhibitors be effective in treating hypertension?

2. A toddler in Africa travels to a remote area with no access to clean drinking water. He drinks sewage water and soon develops severe diarrhea and dies 10 days later of cardiac arrest. Explain the possible physiological cause(s) of his death.

3. A patient with poor blood flow to the kidneys is treated with an ACE inhibitor and goes into renal failure. Explain the reason for the renal failure.

Answer 1

1. Renin is an enzyme in the renin angiotensin system that helps in the formation of angiotensin II. Angiotensin II is a potent vasoconstrictor and causes water retention which causes rise in blood pressure... So if we use renin inhibitors, all these downstream effects are blocked and it would help in reducing the blood pressure

2. The toddler might got acute gastroenteritis which resulted in fluid and electrolytes loss. Loss of potassium might be the cause of the sudden cardiac arrest which can occur in conditions of low potassium levels

3. Normally angiotensin II helps in maintaining the tone of the efferent arteriole in the kidney to maintain the Glomerular filtration pressure. (As the afferent arteriole blood flow is already reduced due to stenosis, the tone of the efferent arteriole is solely responsible for maintenance of the Glomerular filtration pressure)

ACE inhibitors prevent the formation of angiotensin II and the protective effect of this on the efferent arteriole is lost in cases of renal artery stenosis and this causes decreased Glomerular filtration pressure and the patient will ultimately land up in renal failure. So these drugs are contraindicated in renal artery stenosis

Hope this helps..... Thank you!!!