Lab Test Flashcards
What is the purpose of an organ bath?
It’s an ideal way to expose isolated tissue to a known drug concentration and measure responses that are produced.
What does the aqueous solution in an organ bath act as?
A physiological fluid. It is usually 20ml in capacity.
What is a typical solution used in an Organ bath?
Krebs solution.
It has glucose, K, Na, Ca, Mg and Cl- which nourishes the tissue.
What is the purpose of an oxygen tube?
Aeration of krebs solution so tissue has oxygen supply.
Usually 95% oxygen, 5% CO2
How is a constant temperature of 37 degrees maintained?
A waterjacket surrounding the organ bath with a constant flow of warm water, warming the krebs.
What things are needed to keep the tissue alive in an organ bath?
krebs solution
oxygen tube
constant temperature (37 degrees)
What does the force transducer do in an organ bath?
It measures the force produced from the contraction of the tissue. It is connected to the tissue hook.
Where are drugs injected?
The organ bath solution (via a pipette).
What is the resting tension in an organ bath?
The tension when tissue is placed in the bath without contracting. If there is no resting tension, no contraction can be recorded (as there will be slack and this may not signal the force transducer).
What are the 3 types of important info you can obtain from a recording of response of isolated tissue?
- The responses of an isolated tissue to endogenous compounds and to nerve or muscle stimulation may be characterised.
- The mechanism of action of a new drug may be studied.
- The potency of a drug may be determined.
Organ baths were widely used in what year?
1960’s until the 1990’s. Today we look at drug effects on a molecular level, rather than just tissue level.
In an organ bath, do you need to consider ADME processes?
No.
What is good about using mammalian cell cultures?
You can investigate drug receptor interactions and look at the activation of a signal transduction pathways. It can also be used to study the processes that might occur in disease conditions.
Can be used for drug screening and development, testing of toxic drugs, testing of new therapies and large scale manufacturing of biological compounds.
Can also culture for graft/repair purposes.
What are primary cells?
Cells that are used directly from tissue. They are treated with enzymes that break down the extracellular components holding the cells together (dissociation). They then go to tissue growth plate.
What are advantages and limitations of using primary cells?
They are the closest approximation to the ‘real thing’.
BUT they are time consuming and numbers produced can be small and they have a finite life span as they become senescent.
