11. Observation: increased ABP with minimal effect on HR, which increases only with high doses
Explanation of effect of NE on ABP & HR:
NE acts mainly on 1 receptors vasoconstriction PVR
With higher doses of NE, it activates also cardiac 1 receptors some increase in the heart
rate
18. Observation: ABP & HR
late The ABP before returning to base line level
Explanation of the effect of epinephrine on HR & ABP
Epinephrine stimulates 1 , 1, 2 adrenoceptors Beta receptors are more sensitive to the effect of epinephrine
On heart: 1 activation +ve inotropic & chronotropic effects COP leading to increased
ABP
On BV :
- 1 activation vasoconstriction PVR.
- 2 activation vasodilatation PVR
19. •The net effect of these two opposing effects (1 & 2 )
on bl.v is an in PVR
(1 wins at 1st )
•At High concentration:
EPI stimulates 1
•At Low concentration:
EPI stimulates 2
20. AdrenalineNoradrenalineparameters
More increaseMild or no increaseHeart rate
Less increase than
noradrenaline
More increaseBlood pressure
BP decreases before
reaching base line
Reach base line directlyBP before Base line
27. How to confirm the cause of epinephrine reversal?
No epinephrine reversal since propranolol blocks not only cardiac 1 receptors but also vascular
2 receptors
28. What is the effect of propranolol on ABP and HR?
29. Propranolol mechanism as antihypertensive:
1-Block β1 in heart so low COP BP
2- central sympathetic discharge BP
3- Block β1 in kidney Renin BP
4- resetting of Baroreceptors BP
5- Block β2 presynaptic NE release BP
32. Observation:
• Isoprenaline increases HR
• Isoprenaline initially decreases ABP.
• As HR reaches its maximum increase, ABP shows minimal increase before returning to normal
Explanation for the effect of isoprenaline on HR & ABP
• Isoprenaline activates mainly beta adrenoceptor
• It activates cardiac 1 receptors leading to increase in HR & force of contraction
(which increases COP)
• Activation of 2 receptors—Vasodilation decrease in PVR
• The net effect of the two factors (COP & PVR) is a decrease in blood pressure
initially.
• However, when force of contraction is markedly elevated, the increase of COP
overcomes the effect of decrease in PVR and thus ABP starts to increase.
33. Design an experiment to prove the explanation for the effect of Isoprenaline on
HR & ABP
34. Observation: atenolol abolishes the effect of
isoprenaline on HR
The initial ABP-lowering effect of isoprenaline is
maintained, while its pressor effect is abolished
35. PROPRANOLOL FOLLOWED BY ISOPRENALINE
Observation: Propranolol blocks 1 & 2 receptors thus abolishes the
effect of isoprenaline on ABP
37. Observation:
Small dose phenylephrine leads to slight increase in ABP with no effect on HR
High dose phenylephrine increases markedly ABP with decrease in the HR ( reflex bradycardia)
38. Explanation of the effect of phenylephrine on ABP & HR
•Activation of 1 receptors vasoconstrictionPVR
•High dose of phenylephrine marked elevation of ABP
reflex in sympathetic activity. Parasympathetic activity will
take the upper hand HR
39. prove the explanation of the effect of phenylephrine on HR
and ABP
Observation: prazosin abolishes the effect of phenylephrine
on ABP & reflex bradycardia disappears
40. prove that reflex bradycardia is due to relative
increase in parasympathetic activity
Observation: decreased HR is abolished by atropine despite of elevation of ABP
43. Observation:
small doses of acetylcholine lower only ABP
Higher doses produce both in the HR & more
significant lowering of ABP
Explanation for the effect of
acetylcholine on HR and ABP
•on heart: M2 activation - ve chronotropic effect COP
•on BV: endothelial cells M3 activation release of NO from vascular
endothelial cells vasodilatation PVR
• Decrease in heart rate & decrease in PVR lead to ABP
45. ACETYLCHOLINE REVERSAL
1. Inject a test dose of Ach
2. Inject atropine
3.Inject the same dose of acetylcholine
4.Inject a dose of Ach which is 10 times the test dose
46. Explanation for acetylcholine reversal
• Atropine injection A parasympatholytic blocks muscarinic receptors. It blocks
the effect of small dose of Ach.
• Ach injection [big dose] Stimulates nicotinic receptors Nn after muscarinic
receptors have been blocked by atropine ABP
• Due to activation of Nn at :
• Adrenal medulla release epinephrine BP
• Autonomic ganglia release of catecholamines from post-synaptic adrenergic nerve endings
BP
• The BP by Ach [big dose] after muscarinic receptor block [by atropine]
Ach reversal