L11: Vasodilator Pharmacology Flashcards
(35 cards)
How do we get vasoconstriction occurring in smooth muscle
1) voltage gated smooth channels open during depolarisation
2) calcium influx occurs
3) sarcoplasmic reticulum releases stored calcium
4) calcium binds to move the troponin c from the actin binding site
5) myosin head can join the actin binding site = contraction
What other channels apart form the voltage gated calcium channels cause the intracellular calcium to increase and give contraction
Alpha adrenoceptors
What happens when noradrenaline binds to alpha adrenoceptors
1) gQ proteins stimulates IP3
2) IP3 causes the release of stored calcium from the sarcoplasmic reticulum
What are the 2 main groups that vasodilators are classed as
Direct
Indirect
What does indirect vasodilators effect
Block the vasoconstrictors i.e circulating substances
Give examples of indirect vasodilators
Beta blockers
RAAS inhibitor
Endothelins blockers
What are the main action of direct vasodilators
Drugs that interfere with intracellular calcium
What are 3 main targets of intracellular calcium
Voltage gated calcium channels
CGMP (which affects voltage gated calcium channel)
CGMP (which affect actin-myosin contraction)
When can we use vasodilator
Hypertension
Angina
What is angina
The chest pain when there is inadequate coronary blood flow
What are the causes of angina
Obstruction of the coronary artery
What other drugs can be used in angina that are not vasodilator so
Beta blockers : reduce cardiac work
Ivabrodine : reduce pacemaker current
What are the vasodilator drugs used in angina
Glyceryl trinitrate
Isosorbide mono/di nitrate
How do organic nitrates make their action
1) GTN breaks down to give NO
2) NO gives increased CGMP
3) CGMP gives vasodilation by acting on the voltage gated calcium channels
Which vessels does GTN act on
Systemic vessels i.e mostly venous
Coronary vessels
What are the side effects of GTN
Excess vasodilation can lead to hypotension
Headache due to vasodilation in the head
Reduces mobility to GIT which results in constipation
How is GTN administered
Sublingual: spray under the tongue
Transdermal
What other drugs can be used in angina
Calcium channel blockers
Name examples of calcium channel blockers
Amlodipine
Verapamil
Diltiazem
Which vessels do calcium channel blockers act on
Systemic vessels
Coronary vessels
What is the side effect of calcium channel blocker
Flushing
Reduced GIT activity: constipation
What are the other clinical uses of vasodilator
Peripheral vascular disease e.g raynouds disease
Impotence
Hair loss
Stroke
What is Raynouds disease
When the skin vessel vasoconstriction in cold weather
What is impotence
Erection
