05.15 - HTN (Gosmanova) - PP, No reading Flashcards
Increase NaCl delivery to MD increases ___ production
Adenosine
Wet HTN
Essential with Low Renin
Mechanism of Volume Expansion in Glucocorticoid Excess (Cushing’s)
Cortisol excess activates ENaC (same as aldosterone)
Gordon Syndrome is characterized by
Salt-sensitive HTN, HyperK, Metabolic Acidosis
Individuals from INTERSALT had higher ___ compared to rural populations
Average systolic and Diastolic BP
Tx for Genetic PseudoHypoAldosteronism
Triamterene Amiloride
Which activate and which inhibit Renin: B1 rec, Adenosin2 rec, Prostaglandin rec
B1 and PG activate, Adenosin2 inhibits
Activating WNK-1 and Inactivating WNK-4 both cause
Increased activity of NaCl channel and incr Na reabsoprtion (Gordon’s)
Gene mutation leading to Aldosterone Synthetase responsive to ACTH
Glucocorticoid Remediable Aldosteronism
Ouabain acts on
Na/K ATPase
Infusion of Saline in normal kidney patient vs anephric
Small changes of BP in normal; rapid rise in anephric
Dry HTN
Essential with High Renin
Pressure-Natriuresis: ___ is mediator
Changes in interstitial medullary pressure
% of HTN and Normotensive individuals with salt sensitivity
50 and 26
Gordon Syndrome is due to
Constitutive activation of Thiazide-Sensitive NaCl channels in DCT
Inability of kidneys to appropriately excrete Na load
Guyton’s theory
Increase in CO in Essential HTN
does not persist
Effect of Ouabain on SVR and Venous Tone
Increases SVR and Venous Tone
Brenner’s Hypothesis
Reduction in Nephron Mass
Decrased NaCl delivery to MD increases ___ production
NO and PG
All forms of Secondary HTN are characterized by
Salt-sensitive HTN
Ignores role of ANS: Fails to explain incr BP in pre-HTN, where CO incr is mainly driven by SNS activaiton
Cons of Guyton’s Theory
Mechanisms of Salt’s role in HTN
Dec Na excretion, Incr SNS activity, Incr activity of Na-H exchanger, Incr Ca in vascular SM cells
Laragh’s Hypothesis
Some nephron’s are ischemic and produce high renin, while others are not but will have impaired natriuresis from AT2 - Total PRA is diluted/normal
Tx for Liddle’s
Triamterene or Amiloride
Does salt-sensitivity change with age
Yes, increases
Renin and Aldosterone in Secondary HTN
Low Renin and Aldosterone, except Aldosterone Excess obv
Liddle’s disease is due to
Activating ENaC mutation
Psuedohypoaldosteronism Type 2 is aka
Gordon Syndrome
Cause of Liddle’s Syndrome
Constitutive activation of ENaC in DT due to mutaiton in subunit
Decr Na excretion leading to Incr CO is corrected by autoregulation at expense of
Incr SVR and BP
Causes of PseudoHypoAldosteronism (non-Liddle’s)
11B-HSD-2 Defiency of Inhibition
Action of 11B-HSD-2
Breaks down Cortisol
Volume and Renin in Goldblatt Model 1
Renin is high, but volume is normal b/c contralateral kidney is able to excrete excess Na
Change in Pressure-Natriuresis curve with salt-sensivity
Decrease in slope
Worsening condition after ACEi =
Highly suggestive of Bilteral RAS
How does Pseudohypoaldosteronism cause Hypokalemia
Incr Na reabsorption in CD creates favorable gradient for K secretion
Ouabain is activated by
Incr PV
What channel is upregulated in Aldosterone excess that contributes to HTN
ENaC channel reabsorbs Na in CD
Role of Genetics in HTN
70-80% of individuals have positive family history
Channel upregulated in Cushing’s that contributes to BP increase
ENaC channel reabsorbs Na in CD
Goldblatt Model 1
Unilateral RAS w/ 2 normal kidneys - Incr SVR and Right shift in pressure natriuresis - Normal volume
Inc Pre-Load can be due to
Incr Venous Tone or Incr Volume (and therefore total Na)
What inhibits 11B-HSD-2
Chronic licorice ingestion (candies, chewing tobacco)
ACEi’s in Goldblatt Model 1
Reduce BP b/c stenotic kidney is secreting renin
As CKD progresses, revalance of HTN ___
rises
ACEi’s in Goldblatt Model 2
Will not help - In fact, they’ll reduce GFR - RAAS necessary to maintain GFR in this scenario
Renin levels in Essential HTN
20% high, 30% low, 50% normal
MAP = CO x SVR =
DBP + 1/3(SBP-DBP)
Guyton’s theory
Inability of kidneys to appropriately excrete Na load
Pressure-Natriuresis: Changes in Na excretion occur without
changes in GFR
Deficiency in 11B-HSD-2 leads to excess
Cortisol
Activating ENaC mutation
Liddle’s disease is due to
2 mutations that cause Gordon’s
Activation of WNK-1, Inactivaiton of WNK-4
Volume and Renin in Goldblatt Model 2
Both high
Goldblatt Model 2
Biltateral RAS - No off-setting pressure natriuresis
Reduction in Nephron Mass –> ___ –> ___
Systemic/Glomerular HTN –> Acquired Glomerular Sclerosis
Cause of Hyperkalemia in Gordon’s
Reduced distal Na delivery, so decreased K secretion
No salt, no ___, even with ____
No salt, no HTN, even with aging
Age of onset for primary HTN
40s and 50s
Aloows for normal BV despite elevated pressure
Pros of Guyton’s Theory
Pressure-Natriuresis: ___ is the principal site
Outer Medulla (TALH)
What is necessary to maintain GFR in Goldblatt Model 2
RAAS, so ACEi’s are contraindicated
Most common causes of RAS
Atherosclerosis (85%), Fibromuscular Dysplasia (15%)
K and Acid-Base in Secondary HTN
All associated with Hypokalemia and Metabolic Alkalosis except Gordon Sydnrome
Inactivating mutations in 11B-HSD-2 gene
Apparent Mineralocorticoid Excess is due to
2 factors that activate renin release from JGA in response to Renal hypoperfusion
Decr afferent artiolar stretch, Decr NaCl delivery to Macula Densa
T/F: We are all salt-sensitive to some degree
FALSE
SV can be increased by
Incr in Pre-Load or Contractility
Pros of Guyton’s Theory
Aloows for normal BV despite elevated pressure
What normally degrades Cortisol
11B-HSD2
Is peripheral edema common in essential HTN
No
Does Adenosine vasoconstrict or dilate
Vasoconstrict
Apparent Mineralocorticoid Excess is due to
Inactivating mutations in 11B-HSD-2 gene
Prevalence of RAS is higher with
age, DM, PVD, DBP >125
Gordon’s Syndrome mimics
Gitelman’s
How does PseudoHypoAldosteronism cause Metabolic Alkalosis
Hypokalemia causes shift of H+ into tubular cells and then secretion into lumen; Also incr H+ secretion by H pump
What is Pressure Natriuresis
When perfusion press incr., renal Na output incr and ECFV and BV contract to return MAP to baseline
Local factor autoregulation is mediated primarily by
NO
Tx of Gordon’s Syndrome
Thiazide Diuretics
Cons of Guyton’s Theory
Ignores role of ANS: Fails to explain incr BP in pre-HTN, where CO incr is mainly driven by SNS activaiton