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Old 09-10-2016
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Default Macula Densa and Adenosine

FA 2015 says "macula densa cells sense decrease NaCl delivery to DCT => adenosine release => vasoconstriction" on page 535. Is this an error?

Because wikipedia says adenosine is released in response to increased NaCl in the DCT, and I thought renin is the one thats released due to low NaCl in the DCT.
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Old 09-10-2016
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Quote:
Originally Posted by Sniderwes1 View Post
FA 2015 says "macula densa cells sense decrease NaCl delivery to DCT => adenosine release => vasoconstriction" on page 535. Is this an error?

Because wikipedia says adenosine is released in response to increased NaCl in the DCT, and I thought renin is the one thats released due to low NaCl in the DCT.
Are u sure it says ADENOSINE ???
Cause i don't have FA2015 but i don't think that can be adenosine
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Old 09-10-2016
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No, this is not an error. FA is correct.

It is increased NaCl in DISTAL TUBULAR fluid which results from an excessive GFR. This leads to macula densa cells releasing adenosine, which constricts the nearby afferent arteriole, reducing glomerular perfusion and hence GFR.

Low tubular NaCl usually results from decreased GFR, which leads to excessive reabsorption. When this happens, macula densa releases PGE2, which triggers release of renin from the JG apparatus.

You're confusing this with the accumulation of Na inside macula densa which leads to release of adenosine (actually ATP which breaks down to adenosine), due to cells swelling as water follows the Na into the cells.

Does this help?
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Old 09-10-2016
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Originally Posted by mhass24 View Post
No, this is not an error. FA is correct.

It is increased NaCl in DISTAL TUBULAR fluid which results from an excessive GFR. This leads to macula densa cells releasing adenosine, which constricts the nearby afferent arteriole, reducing glomerular perfusion and hence GFR.

Low tubular NaCl usually results from decreased GFR, which leads to excessive reabsorption. When this happens, macula densa releases PGE2, which triggers release of renin from the JG apparatus.

You're confusing this with the accumulation of Na inside macula densa which leads to release of adenosine (actually ATP which breaks down to adenosine), due to cells swelling as water follows the Na into the cells.

Does this help?
It sounds like you are saying increased NaCl in DCT => adenosine release => vasoconstriction => lowered GFR.

However, what FA has is "macula densa cells sense DECREASED NaCl delivery to DCT => adenosine release => vasoconstriction" so I don't see how they could be correct.
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Old 09-11-2016
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You are right, this is an error. Has been corrected in FA 2016 pg 540.
FA 2016 says:
"Macula densa cells sense decreased NaCl delivery to DCT --> increased renin release --> efferent arteriole vasoconstriction --> increased GFR."
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