renal physiology

[nurse258]

I am having trouble understanding renal physiology. How and where do different diuretics work

[Daytonite, BSN, RN]

I am having trouble understanding renal physiology. How and where do different diuretics work

Which ones?

[nurse258]

loops, CA inhibitors, aldosterone antagonist, osmotics

I just want a good site to find all the info or someone to explain the mechanisms to me

thnx

[Daytonite, BSN, RN]

So, what you are looking for is how these diuretics work in relation to the kidneys and not renal physiology.

loop diuretic (organic acids) - These diuretics promote diuresis because they prevent sodium and chloride ions from being transported across the loop of Henle which would normally pull them back into the circulating blood. This results in large amounts of sodium, chloride and water being pulled into the urine. Loop diuretics include furosemide, butetanide, ethacrynic acid and torsemide.

osmotics - Diuretics that can be filtered by the glomerulus but not reabsorbed by the renal tubules. They cannot cross the tubular membranes so they become trapped in the tubular lumens where water migrates toward them and is excreted through the urine along with the diuretic. Sodium reabsorption is unaffected. Electrolyte and acid-base balance is also unaffected. The most commonly used osmotic diuretic is mannitol and it can only be given IV. It is used when there is acute renal failure in order to stimulate urine flow when there is anuria or oliguria and before irreversible renal damage has occurred. It is also used for cerebral edema and glaucoma.

Aldosterone is a hormone that is released from the adrenal cortex and it causes the retention of sodium and, thus, water back into the blood. In order for the body to make aldosterone a precursor must be formed first. It is called renin which in turn becomes angiotensin which in turn becomes aldosterone which in turn becomes aldosterone II. This is called the RAA system for renin-angiotensin-aldosterone. To become active angiotensin must be converted into aldosterone I and Aldosterone II by ACE (angiotensin converting enzyme).

http://cvphysiology.com/Blood%20Pressure/BP015.htm

Aldosterone antagonists specifically block the effect of angiotensin II receptors on blood vessels and in the renal gland which cause blocking of aldosterone secretion stimulated by angiotensin II. The result is lowering of the blood pressure and decreased sodium and water retention. One of the drugs in this class is Cozaar (losartan).

Another group of drugs, which you did not ask about is called ACE inhibitors. They prevent the ACE enzyme from doing its job, thus acting on angiotensin before it even has a chance to become aldosterone.

I do not understand what you mean by CA inhibitors. Can you give me an example of one or more of these drugs?

[CapNurse09]

Hi

Just finished up with this. I used this web site for supplemental information. It explained a lot that our book did not. Just click diuretics or antihypertensives ... it will give you a list to choose from.

http://www.cvpharmacology.com/index.html

Good luck.