RAS, Vasopressin, Kinins

Question 1

What are some peptides involved in cardiovascular regulation?

Answer 1

angiotensin I
angiotensin II
bradykinin

Question 2

What are some peptides involved in cardiovascular regulation?

Answer 2

angiotensin I
angiotensin II
bradykinin

Question 3

What do peptides interact with to control cardiovascular regulation?

Answer 3

effector organs
peripheral nervous system & release of NTs
central nervous system via circumventricular organs

Question 4

What is the renin angiotensin system (RAS)?

Answer 4

angiotensinogen comes from the liver; protease renin acts on angiotensinogen to clip off first 10 amino acids to form AI; converted to active peptide AII via ACE; converted to AIII by removal of end terminal aspartate; AII & AIII primarily act on ATIreceptor (AII also acts on AT2R)

Question 5

What are the two pathways of the RAS system that control BP?

Answer 5

classical ACE, AII, AT1R: causes HTN

counter-regulatory ACE2, A1-7, MAS: counteracts HTN

Question 6

What is renin?

Answer 6

acid protease secreted by kidney; produced by juxtoglomerular apparatus; release leads to HTN (when there is decreased blood flow to the kidney)

Question 7

Where is ACE found?

Answer 7

on the luminal aspect of epithelial cells of the vascular system

Question 8

What do ACEIs and ARBs do?

Answer 8

increase counter-regulatory, cardioprotective pathway

Question 9

What do peptides interact with to control cardiovascular regulation?

Answer 9

effector organs
peripheral nervous system & release of NTs
central nervous system via circumventricular organs

Question 10

What is the renin angiotensin system (RAS)?

Answer 10

angiotensinogen comes from the liver; protease renin acts on angiotensinogen to clip off first 10 amino acids to form AI; converted to active peptide AII via ACE; converted to AIII by removal of end terminal aspartate; AII & AIII primarily act on AT1receptor (AII also acts on AT2R)

Question 11

What are the two pathways of the RAS system that control BP?

Answer 11

classical ACE, AII, AT1R: causes HTN

counter-regulatory ACE2, Ang1-7, MAS: counteracts HTN

Question 12

What is renin?

Answer 12

acid protease secreted by kidney; produced by juxtoglomerular apparatus; release leads to HTN (when there is decreased blood flow to the kidney)

Question 13

function of Mas receptor

Answer 13

mediates vasodilation, anti-inflammation, anti-cell proliferation; stimulates increase in Ca+2 & NO

Question 14

What do ACEIs and ARBs do?

Answer 14

increase counter-regulatory, cardioprotective pathway; pts lose all feedback inhibition; renin & AI increase

Question 15

4 mechanisms that control renin secretion

Answer 15

• -stretch receptors in afferent arteriole respond to decreased stretch for increased renin release
• -macula dense senses decreased Na so increases renin release
• -SNS signals NE release to stimulate beta receptors on juxtaglomerular cells to increase renin release
• -AII, vasopressin, K all inhibit renin release

Question 16

How does angiotensin raise BP?

Answer 16

direct vasoconstriction; increase SNS activity & increase vasopressin; stimulates NE release from sympathetic neurons in PNS; stimulates release of epi from adrenal medulla

Question 17

cardiovascular & adrenal actions of AII & AIII

Answer 17

increase BP, increase HR & contractility; hypertrophy & remodeling
increase aldosterone synthesis/release

Question 18

function of AT1R

Answer 18

mediates most actions of AII, AIII

stimulates phospholipase C to increase Ca+2 (constriction & activation of MAPkinase in remodeling)

Question 19

function of AT2R

Answer 19

stimulates increase in NO and block MAPK; vasodilation & natriuresis; opposes AT1R-mediated vasoconstriction

Question 20

function of Mas recpetor

Answer 20

mediates vasodilation, anti-inflammation, anti-cell proliferation; stimulates increase in Ca+2 & NO

Question 21

mechanism of action of ARBs

Answer 21

competitively antagonize AT1Rs to prevent vasoconstriction & Na retention
residual AT2R activation causes vasodilation & natriuresis

Question 22

How do ARBs affect renin release?

Answer 22

ARB blockade of AT1Rs results in loss of AII feedback inhibition; renin release is promoted leading to production of more AI & AII; metabolized to Ang1-7 by ACE2

Question 23

What is the function of the local RAS system?

Answer 23

vascular smooth muscle: local intrinsic control

brain: NT, regulation of SNS, vasopressin release, regulation of arterial pressure & metabolism

Question 24

What is the cardiovascular action of bradykinin?

Answer 24

vasodilator of arterioles via NO & eicosanoids
*modulates pressure in hypertensive situations but doesn’t contribute to maintenance of basal pressure in normal individuals

Question 25

What are the two causes of diabetes insipidus?

Answer 25

central DI: gene mutation

nephrogenic DI: receptor mutation

Question 26

What is vasopressin released in response to?

Answer 26

low arterial pressure
low fluid vol or increased osmolality
pain/nausea/hypoxia

Question 27

actions of vasopressin

Answer 27

antidiuretic effect: increases permeability of collecting ducts to water at low concentration
direct vasoconstriction: at high concentration
indirect central: acts at area postrema to promote bradycardia

Question 28

vasopressin receptors

Answer 28

V1: cardiac effects, increase Ca
V2: antidiuretic effects, increase cAMP