1/
Is a GFR of zero always = to kidney failure?
How important are glomeruli?
Are we secretly guilty of ignoring the humble tubule?
Let's have a look at the Seahorse, this year's contender for @NephMadness an AGLOMERULAR fish.
#AnimalHouse #NephTwitter @NSMCinternship @AJKDblog
Is a GFR of zero always = to kidney failure?
How important are glomeruli?
Are we secretly guilty of ignoring the humble tubule?
Let's have a look at the Seahorse, this year's contender for @NephMadness an AGLOMERULAR fish.
#AnimalHouse #NephTwitter @NSMCinternship @AJKDblog
2/
How can an aglomerular kidney provide the function of the kidney?
Let's briefly recap the function of the glomerulus and the tubule using what we know of human physiology
How can an aglomerular kidney provide the function of the kidney?
Let's briefly recap the function of the glomerulus and the tubule using what we know of human physiology
3/
How would you expect the composition of the urine of aglomerular fish to compare to that of glomerular fish?
How would you expect the composition of the urine of aglomerular fish to compare to that of glomerular fish?
4/
In 1930 EK Marshall showed that aglomerular and glomerular fish have similar urine flow+ electrolyte/waste composition
“the tubule.. in the aglomerular kidney can carry out most of the functions.. performed by the tubule and glomerulus in the glomerular fish kidney”
In 1930 EK Marshall showed that aglomerular and glomerular fish have similar urine flow+ electrolyte/waste composition
“the tubule.. in the aglomerular kidney can carry out most of the functions.. performed by the tubule and glomerulus in the glomerular fish kidney”
5/
Which begs the question: Do we even need glomeruli?
Are glomeruli more trouble than they are worth?
Which begs the question: Do we even need glomeruli?
Are glomeruli more trouble than they are worth?
6/
Homer Smith postulated that glomeruli evolved as early fish migrated from seawater to freshwater as an adaptation to excrete the excess water load.
Protovertebrates had only renal tubules with a low pressure venous blood supply limiting the rates of water excretion.
Homer Smith postulated that glomeruli evolved as early fish migrated from seawater to freshwater as an adaptation to excrete the excess water load.
Protovertebrates had only renal tubules with a low pressure venous blood supply limiting the rates of water excretion.
7/
Enter the glomerulus with its arterial pressures 💪
High filtration pressure➡️increased capacity for water excretion
Glomeruli became the main blood supply to the tubules making the portal venous system redundant.
Our tubules now rely on glomerular blood flow for perfusion
Enter the glomerulus with its arterial pressures 💪
High filtration pressure➡️increased capacity for water excretion
Glomeruli became the main blood supply to the tubules making the portal venous system redundant.
Our tubules now rely on glomerular blood flow for perfusion
8/
As fish returned to seawater a small number, including the seahorse, lost their glomeruli as excretion of excess water was no longer necessary.
On land, mammals and birds developed the LoH to conserve water.
As fish returned to seawater a small number, including the seahorse, lost their glomeruli as excretion of excess water was no longer necessary.
On land, mammals and birds developed the LoH to conserve water.
9/
Glomeruli are not just important for filtering large volumes of water
They filter many water soluble solutes.
Tubules are more selective in what they secrete.
Glomeruli are sometimes the main mode of elimination for foreign agents eg. drugs
Glomeruli are not just important for filtering large volumes of water
They filter many water soluble solutes.
Tubules are more selective in what they secrete.
Glomeruli are sometimes the main mode of elimination for foreign agents eg. drugs
10/
The selectivity of tubules lead to breakthroughs into basics of renal physiology🏆🥇
Tubules cannot secrete carbohydrates: Inulin (a freely filtered carb)➡️a marker of GFR
P-aminohippuric acid (PAH) is filtered and then almost entirely secreted by the tubule➡️a marker of RPF
The selectivity of tubules lead to breakthroughs into basics of renal physiology🏆🥇
Tubules cannot secrete carbohydrates: Inulin (a freely filtered carb)➡️a marker of GFR
P-aminohippuric acid (PAH) is filtered and then almost entirely secreted by the tubule➡️a marker of RPF
11/
Oddities of nature often steer scientific discovery. Aglomerular fish are no exception! Hopefully more breakthroughs are to come.
The evolution of the kidney may have allowed us to become philosophers; studying this journey calls out to the philosopher in us all!
Oddities of nature often steer scientific discovery. Aglomerular fish are no exception! Hopefully more breakthroughs are to come.
The evolution of the kidney may have allowed us to become philosophers; studying this journey calls out to the philosopher in us all!
12/ Hope you enjoyed my first tweetorial!
Check out the blogpost at ajkdblog.org/2021/03/01/nep…
Coming up soon, let's see how the #Hagfish matches up against the Seahorse. Who will come out on top?
Thanks to @Nephro_Sparks @CRRTiff @drM_sudha @amyaimei
Check out the blogpost at ajkdblog.org/2021/03/01/nep…
Coming up soon, let's see how the #Hagfish matches up against the Seahorse. Who will come out on top?
Thanks to @Nephro_Sparks @CRRTiff @drM_sudha @amyaimei
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