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11 Cards in this Set

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How is Liddle's SYndrome caused?

Autosomal dominant inheritance


Mutation in genes for ENaC (Principal cell - renal)

Autosomal dominant inheritance




Mutation in genes for ENaC (Principal cell - renal)



What occurs in Liddle's syndrome?

Na and fluid retention
-excessive Na and H2O uptake (ENaC)


Leads to expansion of ECF
Hypertension


Hypokalaemia
-abs excess Na (ENaC) drives Vm towards Ena, drives exit of Na and entrance of K (Na/K ATPase)


Metabolic alkalosis
alpha-intercala...

Na and fluid retention -excessive Na and H2O uptake (ENaC), Leads to expansion of ECF, Hypertension



Hypokalaemia. -abs excess Na (ENaC) drives Vm towards Ena, drives exit of Na and entrance of K (Na/K ATPase)



Metabolic alkalosis. alpha-intercalated cell, increased Na abs = driving force for secretion of H = increase pH



Low renin and aldosterone levels

How would the body normally decrease BP?

BP rises:


decreased renin and aldosterone release




low aldosterone reduces trafficking of ENaC




decreased Na reabs


so decreased H2O reabs


so decreased BP

How would the body react to an increase in BP in an individual with Liddle's syndrome?

BP rise:


decreased renin and aldosterone release




but faulty compensation mechanism so can't remove ENaC from membrane




No reduction in Na reabs




Hypertension persists

What is the treatment for Liddle's syndrome?

Amiloride


K+ sparing diuretic




blocks ENaC

Why does spironolactone not work as a treatment for Liddle's syndrome?

It's a mineralcorticoid R antagonist




(MR R binds aldosterone)




Not effective b/c aldosterone already low

What are the symptoms seen in diabetes insipidus?

Polyuria


increased flow rate


upto 23L in 24hrs



Compensatory polydipsia


thirst


dehydration can be a serious issue



Hypernatremia


high Na

What are the 4 types of diabetes insipidus?

What are the causes of central diabetes insipidus?

1. Acquired


infection in brain


head trauma


surgery




2.Congenital


neurohypophyseal DI


67 mutations in AVP gene (production/ function/ trafficking)

What are the causes of nephrogenic diabetes insipidus?

1.Acquired


lithium


-bipolar affective disorder treatment. Toxic to kidney.


Some antibiotics, antifungals, antineoplastic (chemo) agents


Hypokalemia and hypercalciuria


Acute and chronic renal failure



2.Congenital


mutations in AVPR2/AQP2 genes


AVPR2 gene


-X-linked


-impacts on trafficking(dominant) or function (recessive) of protein

What are the treatments of diabetes inspidius?

1.Central


Desmopressin


increases urine osmolality




2.Nephrogenic - difficult as defect lies in kidney so can't respond


Possibilities:


Modulator drugs - corrects misfolding




Pharmacological chaperones - push misfolded proteins to membrane (AQP2)




Cell permeable R antagonists (cGMP and cAMP pathway antagonists - traffick AQP2)




Statins




Prostaglandins




Heat shock protein 90