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==Actions==
==Actions==
−Alpha-2 agonists have a wide range of actions, due to the presence of alpha-2 receptors throughout the body. The actions most useful pharmacologically are '''sedation''', '''anxiolysis''' and '''analgesia'''. The drugs also have a huge '''anaesthetic sparing effect''', reducing MAC by 50-95%. They also give '''muscle relaxtion'''.
+Alpha-2 agonists have a wide range of actions, due to the presence of alpha-2 receptors throughout the body. The actions most useful pharmacologically are '''sedation''', '''anxiolysis''' and '''analgesia'''. The drugs also have a huge '''anaesthetic sparing effect''', reducing MAC by 50-95%. They also give '''muscle relaxation'''.
Other systems affected by alpha-2 agonists include:
Other systems affected by alpha-2 agonists include:
* <u>Cardiovascular System</u>
* <u>Cardiovascular System</u>
** Post synaptic alpha-2 effects and non-selective action on alpha-1 receptors cause vasoconstriction, hypertension and reflex bradycardia.
** Post synaptic alpha-2 effects and non-selective action on alpha-1 receptors cause vasoconstriction, hypertension and reflex bradycardia.
−** Pre-synaptic inhibition of noradrenaline release gives a reduced sympathetic outflow. This dexreases heart rate and offsets vasoconstriction.
+** Pre-synaptic inhibition of noradrenaline release gives a reduced sympathetic outflow. This decreases heart rate and offsets vasoconstriction.
* <u>Respiratory System</u>
* <u>Respiratory System</u>
** The drugs cause mild depression of the respiratory systsem.
** The drugs cause mild depression of the respiratory systsem.
** The response to hypercapnoea is reduced.
** The response to hypercapnoea is reduced.
* <u>Gastrointestinal Tract</u>
* <u>Gastrointestinal Tract</u>
−** Alpha-2 agonists cause extreme vomitting in dogs and cats. [[#Xylazine|Xylazine]] is the worst culprit for this.
+** Alpha-2 agonists cause extreme vomiting in dogs and cats. [[#Xylazine|Xylazine]] is the worst culprit for this.
** Huge reductions in gut motility occur following drug administration, as well as decreased salivation and secretion.
** Huge reductions in gut motility occur following drug administration, as well as decreased salivation and secretion.
* <u>Endocrine System</u>
* <u>Endocrine System</u>