Essay on The Action of Ans-Related Drugs on Smooth Muscle

1355 Words Apr 16th, 2011 6 Pages
The action of ANS-related drugs on smooth muscle


In the following experiment, the key objective is to compare the mechanical changes in tonic force by longitudinal smooth muscle after the addition of different concentrations of the drugs noradrenaline and acetylcholine. Peristalsis is the wave of muscle contractions that allow circular muscles to constrict the gut and longitudinal muscles to shorten it in an attempt to move the food bolus towards the rectum. A series of dilutions were prepared for both drugs to deduce the effect this would have on the contractions of the mammalian gut. These were added, in turn, to Ringers solution containing the gut (a solution resembling blood serum in its salt constituents used for
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It is distinguishable that when acetylcholine is added, the tonic force in the gut increases as the concentration increases. This is especially true at higher concentrations of acetylcholine, eg at a concentration of 1x10-5, the tonic force of the gut was 12.6mN. Conversely, at higher concentrations of Noradrenaline the tonic force in the gut decreases. The gut does not show any change in tonic force at lower concentrations, there is minimal or no change which can be determined from the graph. The tonic force of the gut at the highest concentration of 10-5 was -4mN which is significantly lower in comparison to what acetylcholine portrayed. So as concentration of noradrenaline increases, the tonic force in the gut decreases whilst as concentration of acetylcholine increases, the tonic force of the gut also increases.


1) The results obtained demonstrate that increasing concentration of acetylcholine increases tonic tension in the section of gut, conversely increasing noradrenaline concentration decreases tonic tension of the gut.

2) Both drugs do not influence the rate of rhythmic contractions yet they alter force and peak. The rate should remain fairly constant as it signifies the transmission of impulses being sent from the nervous system, any slowing in rate would suggest deprivation of nerve supply yet this is not the case as the same gut is used for both drugs and all concentrations.

3) The amplitude
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