Practical 4: Rat Ileum Flashcards
Discuss the health and safety implications of atropine
- extremely toxic (alkyloid from atropa belladonna- deadly nightshade)
- so will use small concentration- 2nM and wear gloves and safety specs
What is krebs solution?
buffer with same concentrations of ions as found in interstitial body fluid and glucose for energy
what is the tissue bath supplied with?
95% O2 and 5% CO2 bubbling through
What is the purpose of the carbon dioxide being supplied to the tissue bath?
Maintains pH by equilibriating with sodium bicarbonate (Na2CO3), giving a pH of 7.4
why must the pH remain stable at 7.4?
calcium ion precipitation may otherwise occur
what temperature is the tissue bath?
37 degrees celcius
How is the tension development of the ileum piece recorded?
on a workstation through a force displacement transducer- linked to a powerlab system
describe the first part of the experiment, where methacholine is used- v. brief
- use a number of different stock solutions of methacholine (O2/CO2 bubbling through mixes it)
How is desensitisation avoided in the first part of the experiment?
the rat ileum is only in touch which methacholine for 30 seconds before the bath is emptied and methacholine is washed off
why must the krebs solution always be at 50ml?
to maintain agonist/ antagonist concentration
Briefly, what happens in the second part of the experiment?
add krebs solution and 2nM of atropine to the ileum and leave it to equilibriate for 10 minutes
- after the tissue has equilibriated, repeat part 1
