Analysis of data from the practical class (guinea-pig ileum experiments) - Lab Report Example

Analysis of data from the practical (guinea-pig ileum experiments On a graph draw your suitably-labelled log concentration – response curves and list the two EC50 values (with units) obtained by your set of 3 students (i.e. for the agonist in the absence and presence of the unknown drug). Graph 1: Comparison of the dose-response curves for contraction in the absence and presence of unknown drug •—•, Contraction (Ach alone); ×—× presence of unknown drug xThe fractional deteriorationAch alone curve = baseline 5% maximum= 100%The graph shows that with acetycholine, there was a large displacement between the two curves before the drug was introduced and after it was introduced.

The displacement witnessed is an evidence of contractile response generated by the action potential of the acetycholine. 2. Once all the practicals have ended you will be supplied with a spreadsheet of all the class results. Fill in the table (see next page) for all 4 types of agonist/antagonist combination used. Using appropriate statistical tests on the class data, examine whether in each case the presence of the antagonist increased the log EC50 value of the agonist significantly (in other words, made it less negative)*.

Agonist/antagonist combinationLog EC50 AGONIST ALONELOG EC50 for agonist in presence of antagonstDose ratioT valueP valueSig differenceAch/ antagonist x-7.8785-5.839291667109.44812.3646242513.77701E-05Yes Ach/antagonist y-7.78919-7.545881.7511062.3646240.088654No Histamine/antagonist x-7.44969-7.13542.0620142.3646240.061504NOHistamine/antagonist y-7.55681-5.845551.441372.85E-052.364624YESThe difference between means was judged to be statistically significant if the t-value for experiment was greater than the critical t valueQuestion 3. (i) To which drug classes do antagonists X and Y belong (i.e. which receptor types do you think they act upon)?

X - Ganglionic blockers acting on cholinergic nicotinic receptor.Y - H2 antagonists acting on H2 receptors. This is because the drugs at the H2 receptors where they inhibit the action of histamine. (ii) With reference to the class practical results in the table (page XX), describe in detail what the experimental evidence is for your answers to question 3(i). This justification of your conclusions is a very important part of this practical write-up.X- Due to the introduction of the drug x, there was contraction response on acetycholine as seen by the less negative values after the introduction of the drug.

He drug acts on cholinergic nicotinic receptors, where acetycholine derives it actions. Y-As a result of the introduction of the drugs, the histamine action was strongly altered as seen by less negative values than in the absence of the drugs. In which case, it can be concluded that they are H2 antagonists because they are the ones that inhibit the action of histamine at H2 receptors. Through the action of H2 receptors, histamine is able to secrete gastric juice. (iii) After using a pharmacology text book and your lecture notes, write down a possible name for drug X and a possible name for drug Y.

Drug x – benzohexoniumDrug y – Pepcid 4. The experimental protocol for this practical involved determining two log concentration – response curves, the first one in the absence of the unknown antagonist and the second one in its presence. Could this experimental protocol lead to any error and, if so, and how might it be avoided (e.g. by modifying the protocol)?Paradoxical potentiating effects: Very low concentrations of aacetycholine sometimes produce a potentiation instead of antagonism and this would interfere with the measurements.

More attention should be given when measuring the concentration to ensure that it is enough.