vasoactive peptides

Question 1

what are vasoactive peptides

Answer 1

autocoids(act like local homrone, have a brief duration, and act near their sites of biosynthesis)with significant actions on vascular smooth muscles as well as other tissues
— include vasoconstriction, vasodilations, and peptides with missed effects

sometimes secretor cells, secret peptides that resule in action of adjacent cells

Question 2

what is vasopressin and their effect at different concentrations

Answer 2

shares a dual physiologial effect of vasoconstriction(pressor) and antidiuresis(volume) thus also know as antidiuretic hormone

at low conco only have antidiuresis effect

released by posterior pituitary in response to falling blood pressure on rising plasma tonicity(reducing in blood volume)

• important role in long term control of blood pressure regualtionof arterial pressure by its vasoconstriction actions

Question 3

what is angiotensin

Answer 3

potent vasoactive hormone, important in blood pressure homeostasis

there are AT1,2,3
AT 2 is the most active
they are present in circulation
-synthesisde from protein precusrosr called angiotensiongen by the action of resin, whci is released from the kidney

Question 4

what are facros that affec the blood pressure

Answer 4

cardia output :: heart rate, contractility, (blood volume and venous return)(filling pressure)

and

peripheral resistance: arteriolar tone

Question 5

what is pre load and after load

Answer 5

pre load is the stretching of cardia muscles before contraction, associated with ventricular filling

after load is the force against which the heart has to contract to effect the blood , associated with peripheral resistance

Question 6

flow relationship with difference in the pressure between 2 points AND resistance

Answer 6

directly proportional and inversly proportional to the resistance

Question 7

list the formation of AT and the enzyme needed for each AT

Answer 7

ATensinogen TO 1: renin
at1-at2: ACE
2-3: aminopeptidase A
3-4: aminopeptidase N

Question 8

what is the emchanism of action of ATII receptors

Answer 8

ATII receptors are ATSMALL1 AND ATSMALL2

ATSMALL1- are g protein receptors coupled to many transduciton pathways,
phospholipase CIP3/DAG pathway, tyrosine phsophorylation pathways(JAK/STAT) and mediate most known action at AT - vasoconstriction

ATSMALL2 - GPCR, functional roles are not clearly established

Question 9

what are actions that happen after ANGIOTENSIN II is formed

Answer 9

vasoconstrition that caused blood pressure to increase
aldosteron sectreion that results in the NA retention and rise in blood volume and rise in blood pressure

Question 10

factors that decrease renin relase

Answer 10

blood pressure rise
blood volumen rise
na retention

Question 11

factors that increase renin release

Answer 11

blood pressure decrease
blood volume fall
na depltetion

Question 12

what are the effect of angiotensin renin on cardiovascular system

Answer 12

increase blood pressure
- this increase is more than noradrelaine
rapid onset when given in iv
acts mainly by contracting the arteriolar smooth muscles
central action on are of the postrema in the medulla, oblongata to increase sympathetic discharge and to reduce vagal tone to the heart
-reset baroreflec to a higher pressure
- facilitates sympathetic transmission by increasing release and reducing uptake of noradrenaline

Question 13

what are the effect of angiotensin renin on adrenal glands

Answer 13

increaes the adrenaline release from the adrenal medulla
- stimulaets aldostrone secretion in the adrenal cortex
- renin angiotensin system is a major regulator of aldosterone secretion

Question 14

what are the effect of angiotensin renin on kidney

Answer 14

causes renal vasoconstriction
increases na+ absorbtion in the proximal tubules
inhibits renin secretion

Question 15

what are the effect of angiotensin renin on the central nervous system

Answer 15

action on the area postrema leading to increase in blood pressure
- stimulates drinking(dipogenic effect)
increase secretion of vasopressin and adrenocricotrophic hormone(ACTH)

Question 16

list the clinial use of angiotensin

Answer 16

given by slow iv infusion
- only limited use as an alternative to sympathomimetic amine
- pressor effect well sustained and unlikely to be accompanied by cardiac arrhythmia
– suitable for hypertensive crisis during anaesthesia when the use of astecholamine may cause cardia arrhythmia

Question 17

what are the ways to antagnoise ATII

Answer 17

1. angiotensin converting enzyme inhibitor
2. angiotesin receptor antagonist
   3.renin inhibitor

Question 18

list the angiotensin converting enzyme inhibitor

Answer 18

captopril
enalopril
lisinopril

Question 19

angiotenin receptor antagnoist

Answer 19

saralsin, losartan, valsartan, candesartan

Question 20

renin inhibitor

Answer 20

aliskiren

Question 21

what are the effects of ACE inhibiton

Answer 21

decrease ACE

prevent inhibition of brandykinin
thus increase in NO and PG
vasodilation
thus decrease in blood pressure

Question 22

therapeutic use of ACE inhibitors

Answer 22

1. hypertension
   maximal lowering og blood pressure may take several week sto develop
   when used alone, lower blood pressure significantly in abt 50% of patients with moderate essential hypertension, comparable to thiazide diuretics, or b blocker
2. chrnoic congestive heart failure
   induce arterolar dilation, thereby reducing afterload
   induce venodilations, reducing preload
   thus increase cardiac output, reduce signs and symptoms of congestion, increase exercise tolerance

Question 23

ATII ATSMALL1 antagonist what does it do

Answer 23

the sartans= angiotensin receptor blockers
- non peptide, potent and specific antagonist against ATII action on ATSMALL1 receptors

• orally active with no agnoist activity
• treatment of hypertension with similar effectiveness to ACE inhibitor but lower incidence of cough
• also alternative to ACE inhibitor in treatment of heart failure

—- contraindication: pregnancy

Question 24

renin inhibior

Answer 24

first non peptide, orally active renin inhibitor approved for treatment of hypertension, effective as monotherapy

– long duration of action lasting up to 4 weeks after therpahy is stopped
- combined with other antihypertensive resulting in greater therapeutics efficacy without adverse drug interactions

Question 25

what are vasopressin route of action

Answer 25

mediate thur the receptors of vasopressin
receptors

v1 receptors found in smooth muscles cells and mdeicate vasoconstriction

v2 receptors: found in renal tubules cells and mediate antidiuresis thruogh increased water permeability and water absorption

v2 receptors found outside the kidnes mediate the release of coagulation factor VIII and von willebrand factor

Question 26

what are the vasopressin receptor agonist

Answer 26

vasopressin - weak selectivity, short duration, injected im or iv

selepressin: v1 selective, being developed for us in septic shock

desmopressin : v2 selective, longer duration of action, nasal spray

Question 27

clincial use of vasopressin receptor agonisyt

Answer 27

ADH sensitve diabetes insipidus
- provides effective and immediate therapy with reduction of urine volume to normal
- desmopressin, drug of choice
- bc 12 times more potent and no pressor effect
can be administered intransally rather than injection(therapy is life long)
- longer plasma half life than vasopressin
- may also be used to treat persistent nocturnal enursis in older children and adults

Question 28

list the vasopressin antagonist

Answer 28

conivaptan
- non selective
-approved ofr treatment of hypoantremia caused by syndrome of inappropriate adh(SIADH)

tolvaptan
- 30 fold higher affinity for v2 than v1
- approved for treatment of hyponatremai associated with congestive heart failure and SIADH