Epinephrine
Aim
To study the effect of Epinephrine on anaesthesised dog’s blood pressure
Instruments Required
- Animal- Dog
- Anaesthetic Agents-
- Barbiturates
- Chloralose
- Urethane
- Paraldehyde
- Magnesium Sulphate
- Chemicals/Drugs and Solutions Used-
- Epinephrine
- Isotonic Saline (0.9%)
- Equipment Used-
- Manometer
- Kymograph
- Arterial Cannula
- Venous Cannula
- Tracheal Cannula
- Bull Dog Clamp
- Screw Clamp
- Three way stop clock
- Brodie’s Tambour
- Reservoir bottle for citrate solution
- Respiratory pump
- Dissection instruments
- Syringe
- Stethoscope
- Pressure Transducer
- Data Acquisition System
- Computer Display
- Electrical Stimulator
Procedure
- A dog is weighed and anaesthesised using intravenous route.
- Dog is fixed on table in supine position
- Left Carotid artery is cannulated and connected to a blood pressure recorder
- Right femoral vein is cannulated with a catheter to inject drugs
- Neck is dissected to expose carotid arteries and vagus nerves
- Arterial cannula is inserted into left common carotid artery for recording
- Vagus nerve is cut into central and peripheral end
- Drugs are injected one by one into femoral vein for recording of BP and HR.
- Recording of BP and HR is indicated by black and red lines.
- The recordings are traced and analysed.
Observation
- Adrenaline acts on -α1,α2,β1,β2,β3
- When adrenaline is given intravenously, initial concentration of adrenaline is high. So, it will act on α1, β2.
- But actions of α1 (vasoconstriction), will predominate over actions of β2 (vasodilatation). So, there will be rise in blood pressure.
- Within few seconds, level of adrenaline will decrease due to its rapid metabolism and neuronal re-uptake.
- At lower concentrations, only action of β2 will predominate. So only fall in Blood pressure seen.
- This is called biphasic response
Nor Epinephrine & Isoprenaline
Aim
To study the effect of Norepinephrine & Isoprenaline on anaesthesised dog’s blood pressure
Instruments Required
- Animal- Dog
- Anaesthetic Agents-
- Barbiturates
- Chloralose
- Urethane
- Paraldehyde
- Magnesium Sulphate
- Chemicals/Drugs and Solutions Used-
- Norepinephrine
- Isoprenaline
- Isotonic Saline (0.9%)
- Equipment Used-
- Manometer
- Kymograph
- Arterial Cannula
- Venous Cannula
- Tracheal Cannula
- Bull Dog Clamp
- Screw Clamp
- Three way stop clock
- Brodie’s Tambour
- Reservoir bottle for citrate solution
- Respiratory pump
- Dissection instruments
- Syringe
- Stethoscope
- Pressure Transducer
- Data Acquisition System
- Computer Display
- Electrical Stimulator
Procedure
- A dog is weighed and anaesthesised using intravenous route.
- Dog is fixed on table in supine position
- Left Carotid artery is cannulated and connected to a blood pressure recorder
- Right femoral vein is cannulated with a catheter to inject drugs
- Neck is dissected to expose carotid arteries and vagus nerves
- Arterial cannula is inserted into left common carotid artery for recording
- Vagus nerve is cut into central and peripheral end
- Drugs are injected one by one into femoral vein for recording of BP and HR.
- Recording of BP and HR is indicated by black and red lines.
- The recordings are traced and analysed.
Observation
- Noradrenaline:
- NE has predominant alpha effects
- NO BETA-2 EFFECT
- So no fall in BP
- Hence no Biphasic effect
- Isoprenaline
- Beta1(Tachycardia), beta2-BV of SK muscles, renal & mesenteric vascular bed-vasodilatation.
- Slow metabolism-Slow reversal to the baseline
Alpha Blocker/Dales Vasomotor Reversal
Aim
To study the effect of alpha blockers on anaesthesised dog’s blood pressure
Instruments Required
- Animal- Dog
- Anaesthetic Agents-
- Barbiturates
- Chloralose
- Urethane
- Paraldehyde
- Magnesium Sulphate
- Chemicals/Drugs and Solutions Used-
- Alpha Blockers
- Isotonic Saline (0.9%)
- Equipment Used-
- Manometer
- Kymograph
- Arterial Cannula
- Venous Cannula
- Tracheal Cannula
- Bull Dog Clamp
- Screw Clamp
- Three way stop clock
- Brodie’s Tambour
- Reservoir bottle for citrate solution
- Respiratory pump
- Dissection instruments
- Syringe
- Stethoscope
- Pressure Transducer
- Data Acquisition System
- Computer Display
- Electrical Stimulator
Procedure
- A dog is weighed and anaesthesised using intravenous route.
- Dog is fixed on table in supine position
- Left Carotid artery is cannulated and connected to a blood pressure recorder
- Right femoral vein is cannulated with a catheter to inject drugs
- Neck is dissected to expose carotid arteries and vagus nerves
- Arterial cannula is inserted into left common carotid artery for recording
- Vagus nerve is cut into central and peripheral end
- Drugs are injected one by one into femoral vein for recording of BP and HR.
- Recording of BP and HR is indicated by black and red lines.
- The recordings are traced and analysed.
Observation
- After biphasic response if we administer non-selective alpha blocker
- It blocks the alpha receptors, hence alpha-1 mediated vasoconstriction does not occur
- Only beta-2 mediated action occurs
- So only fall in blood pressure is seen, rather than biphasic response.
- This phenomenon is known as Vasomotor Reversal of Dale
Beta Blocker/Dales Vasomotor Rereversal
Aim
To study the effect of Beta Blockers on anaesthesised dog’s blood pressure
Instruments Required
- Animal- Dog
- Anaesthetic Agents-
- Barbiturates
- Chloralose
- Urethane
- Paraldehyde
- Magnesium Sulphate
- Chemicals/Drugs and Solutions Used-
- Beta Blocker
- Isotonic Saline (0.9%)
- Equipment Used-
- Manometer
- Kymograph
- Arterial Cannula
- Venous Cannula
- Tracheal Cannula
- Bull Dog Clamp
- Screw Clamp
- Three way stop clock
- Brodie’s Tambour
- Reservoir bottle for citrate solution
- Respiratory pump
- Dissection instruments
- Syringe
- Stethoscope
- Pressure Transducer
- Data Acquisition System
- Computer Display
- Electrical Stimulator
Procedure
- A dog is weighed and anaesthesised using intravenous route.
- Dog is fixed on table in supine position
- Left Carotid artery is cannulated and connected to a blood pressure recorder
- Right femoral vein is cannulated with a catheter to inject drugs
- Neck is dissected to expose carotid arteries and vagus nerves
- Arterial cannula is inserted into left common carotid artery for recording
- Vagus nerve is cut into central and peripheral end
- Drugs are injected one by one into femoral vein for recording of BP and HR.
- Recording of BP and HR is indicated by black and red lines.
- The recordings are traced and analysed.
Observation
- Reversing the action which happened in Vasomotor reversal of Dale
- When we give non-selective Beta Blocker(instead of non selective alpha blocker)
- It blocks the beta-2 receptors, hence beta-2 mediated vasodilatation will be blocked
- Now if we give Adrenaline again, Only alpha-1 mediated action occurs.
- Vasoconstriction takes place leading to rise in blood pressure rather than biphasic response.
- This phenomenon is known as Re-reversal of Vasomotor Reversal of Dale
Ephedrine
Aim
To study the effect of Ephedrine on anaesthesised dog’s blood pressure
Instruments Required
- Animal- Dog
- Anaesthetic Agents-
- Barbiturates
- Chloralose
- Urethane
- Paraldehyde
- Magnesium Sulphate
- Chemicals/Drugs and Solutions Used-
- Ephedrine
- Isotonic Saline (0.9%)
- Equipment Used-
- Manometer
- Kymograph
- Arterial Cannula
- Venous Cannula
- Tracheal Cannula
- Bull Dog Clamp
- Screw Clamp
- Three way stop clock
- Brodie’s Tambour
- Reservoir bottle for citrate solution
- Respiratory pump
- Dissection instruments
- Syringe
- Stethoscope
- Pressure Transducer
- Data Acquisition System
- Computer Display
- Electrical Stimulator
Procedure
- A dog is weighed and anaesthesised using intravenous route.
- Dog is fixed on table in supine position
- Left Carotid artery is cannulated and connected to a blood pressure recorder
- Right femoral vein is cannulated with a catheter to inject drugs
- Neck is dissected to expose carotid arteries and vagus nerves
- Arterial cannula is inserted into left common carotid artery for recording
- Vagus nerve is cut into central and peripheral end
- Drugs are injected one by one into femoral vein for recording of BP and HR.
- Recording of BP and HR is indicated by black and red lines.
- The recordings are traced and analysed.
Observation
- Mixed acting sympathomimetics
- Acts by releasing catecholamines and direct effects on adrenergic receptors
- Ephedrine mainly stimulates Alpha 1 and Beta 1 receptors
- No beta 2 Action
- Alpha 1 increases BP
- Tachyphylaxis
Tachyphylaxis
- Rapid development of tolerance when the drug is given in quick succession
- ‘Tachy’ means ‘fast’, and ‘phylaxis’ means ‘protection’
- It refers to rapid development of tolerance when doses of a drug is repeated in quick succession resulting in marked reduction in responses.
- Usually seen in indirectly acting drugs such as ephedrine, tyramine and nicotine.
- These drugs acts by releasing catecholamines in the body synthesis of which is unable to match the rate of release: stores get depleted.
- Other mechanisms like slow dissociation of the drug from its receptor, desensitization/internalization or down regulation of receptor, etc. and/or compensatory homeostatic adaptation
Atropine
Aim
To study the effect of Atropine on anaesthesised dog’s blood pressure.
Instruments Required
- Animal- Dog
- Anaesthetic Agents-
- Barbiturates
- Chloralose
- Urethane
- Paraldehyde
- Magnesium Sulphate
- Chemicals/Drugs and Solutions Used-
- Atropine
- Isotonic Saline (0.9%)
- Equipment Used-
- Manometer
- Kymograph
- Arterial Cannula
- Venous Cannula
- Tracheal Cannula
- Bull Dog Clamp
- Screw Clamp
- Three way stop clock
- Brodie’s Tambour
- Reservoir bottle for citrate solution
- Respiratory pump
- Dissection instruments
- Syringe
- Stethoscope
- Pressure Transducer
- Data Acquisition System
- Computer Display
- Electrical Stimulator
Procedure
- A dog is weighed and anaesthesised using intravenous route.
- Dog is fixed on table in supine position
- Left Carotid artery is cannulated and connected to a blood pressure recorder
- Right femoral vein is cannulated with a catheter to inject drugs
- Neck is dissected to expose carotid arteries and vagus nerves
- Arterial cannula is inserted into left common carotid artery for recording
- Vagus nerve is cut into central and peripheral end
- Drugs are injected one by one into femoral vein for recording of BP and HR.
- Recording of BP and HR is indicated by black and red lines.
- The recordings are traced and analysed.
Observation
- Parasympatholytic- antimuscaranic agent
- No effect on BP – less cholinergic innervations in blood vessels
- Tachycardia
Synthetic Atropine Derivatives and theirs Uses:
- Cyclopentolate: Mydriatic
- Isopropamide: Antisecretory-antispasmodic
- Biperiden- Antiparkinsonian
- Tolterodine- Vesicoselective