PHARMACOLOGY

 BIOASSAY OF ACETYLCHOLINE ::

Principle ::

Potency of the test sample is compared with that of the standard preparation There are several biological methods for its assay 

1.Rectus Abdominis Muscle of Frog ::

Dissect the rectus muscle and arrange the assembly as per assay of d-tubocurarine Plot log dose response curve and find out the potency of the sample of acetylcholine 

2.Cat s Blood Pressure ::

A cat is anaesthetized with suitable anaesthetic The carotid artery is cannulated for recording BP Femoral vein is cannulated for injecting acetylcholine Trachea is cannulated for giving artificial respiration Acetylcholine produces a fall in BP by dilating peripheral blood vessels This principle is utilised for its bioassay The extent to which BP falls due to the test sample is compared with the fall by the standard preparation 

3.Guinea-pig ileum ::

Guinea -pig is killed by a blow on the head and bled to death The abdominal wall is dissected out so as to isolate the ileum the faecal matter mesentery and bood vesseles are removed from the priece of ileum it is ligated on both sides and suspended in mammalian organ bath containing Tyrode solution maintained at 37.0.C and oxygenated continuously Acetylcholine contracts the ileum This principle is utilised for its bioassay The extent of contraction produced by the test sample is compared with the standard preparation of acetylcholine 

4.Anaesthetised Rats ::

Compare the extent of fall in BP of the test sample with that produced by the standard preparation 

5.Leech Muscle ::

Compare the contractions produced by the standard and test samples on eserinised dorsal muscle of the leech This muscle is highly sensitive (picograms ) to acetylcholine 

6.Isolate Heart Preparations ::

Rabbit s auricle frog s heart rabbit s heart or venous merceneria s heart is used Ach decreases the force and rate of the heart 

7.Rabbit s Intestine and Tracheal Chain ::

Ach contracts these tissues