Vasoactive Peptides Flashcards
Which vasoactive peptides are important vasoconstrictors?
- angiotensin II
- vasopressin
- endothelins
- neuropeptide Y
Which vasoactive peptides are important vasodilators?
- bradykinin
- natriuretic peptides
- vasoactive intestinal peptide
- substance P
- neurotensin
- CGRP
Describe biosynthesis of angiotensin II.
- angiotensinogen is synthesized in the liver
- renin is secreted in the kidneys and converts it to angiotensin I
- angiotensin I is converted to angiotensin II by ACE (angiotensin converting enzyme)
Where is renin synthesized and stored?
in granular cells of the juxtaglomerular apparatus
Renin secretion is increased in response to what?
- diminished NaCl flux through NKCC transporters in the macula densa
- B1 stimulation of granular cells
- low BP, which is sensed by baroreceptors in the afferent arteriole wall
What are the primary actions of angiotensin II?
- increase peripheral resistance
- increase fluid volume
What is the effect of ACE inhibitors on preload and afterload?
they decrease both preload and afterload
Drugs ending in “-pril” belong to which class?
they are ACE inhibitors
Through what three mechanisms do ACE inhibitors reduce BP?
- inhibit ATII-mediated vasoconstriction
- inhibit ATII-mediated release of aldosterone, which results in lowering blood volume
- inhibit ATII-mediated bradykinin breakdown, maintaining it’s vasodilative effect
Why can ACE inhibitors lower BP even in those without elevated renin levels?
because it also serves to maintain elevated bradykinin levels, which has a vasodilative effect
What are the three most significant adverse effects of ACE inhibitors?
- dry, hacking, non-productive cough
- angioedema or anaphylaxis (high bradykinin)
- hyperkalemia (low aldosterone)
Which group of drugs have a signature side effect of dry, hacking, non-productive cough?
ACE inhibitors
What group of drugs are named with the suffix “-sartan”?
angiotensin receptor antagonists
How do angiotensin receptor antagonists compare to ACE inhibitors?
the angiotensin receptor antagonists don’t have the same effect on bradykinin metabolism, so they are less effective at reducing BP but also don’t cause cough or pose a risk for angioedema
Aliskiren
the only renin inhibitor
Bosentan
an endothelin receptor antagonist
Aprepitant
a neurokinin-1 receptor antagonist developed as a potential analgesic but more useful in preventing chemotherapy-induced emesis
Desmopressin
a vasopressin agonist with V2 selectivity
Conivaptan
a vasopressin receptor antagonist
How are kinins formed?
from kininogens by the action of kallikreins
Most kinin biological effects are mediated by which receptor?
- most effects linked to B2
- B1 receptors have limited tissue distribution and function
What are the inflammatory effects of kinins?
(all but fever)
- redness
- pain
- swelling
- heat
Drugs ending in the suffix “-pressin” belong to which class of drugs?
they are vasopressin agonists
What disease does a vasopressin deficiency cause?
diabetes insipidous
