This program is highly interactive and simulates experiments,
which may be performed on the isolated perfused mammalian heart
(Langendorff preparation). Introduction and Methods sections cover
the removal of the heart, setting it up to record ventricular contractile
force, heart rate and coronary blood flow and the administration
of drugs.
In the Experiments section simulated data, derived from actual
data, is presented on a screen display which emulates a chart recorder.
Students 'design' experiments by choosing, from a menu, a range
of pharmacological agents which may be administered either alone,
or in combination with an antagonist or potentiator. Each trace
represents several minutes of recording and thus allows students
to access a large amount of data in a short period of time. A facility
to compare traces of 'drug X alone' with drug X + antagonist Y or
drug X + potentiator Z is available. This allows easy visual comparison
of qualitative effects and of course more accurate measurements
can be taken from the screen.
The program covers:
1 effects of drugs: sympathomimetics (adrenaline, noradrenaline,
salbutamol, clonidine, phenyl-ephrine, dobutamine) antagonists (propranolol,
yohimbine atenolol, prazosin, butoxamide, phentolamine) potentiators
(cocaine); parasympathomimetics (acetylcholine, carbachol, methacholine,
nicotine) antagonists (atropine, amitryptyline, hexamethonium) potentiator
(neostigmine); cardiac glyco-sides (digoxin, ouabain); coronary
vasodilators (nitrogly-cerine, adenosine (antagonists: theophylline,
dipyridamole), histamine (antagonists: cimetidine, mepyramine),
verapamil;
2. effect of ions: (high and low concentrations of calcium, potassium
and sodium)
3. effect of increasing pre-load on contractile (ventricular) force
(Starlings Law)
The simulated responses (heart rate, ventricular force and coronary
blood flow) are derived from actual experimental data and presented
in high resolution colour graphics in a form comparable to that
of a chart recorder. The program contains textual information describing
the preparation and experimental method and an editable on screen
help facility allows teachers to tailor the information-content
of the program to specific groups of students. The package also
includes suggested student assignments.
It is envisaged that the program could be used in a number of ways:
to better prepare students who will the perform the practical at
a later date; to debrief students after they have performed the
practical; as a ‘fallback’ to provide data for students
whose experiments were unsuccessful; as an alternative to the practical,
though it should be remembered that different learning objectives
may be achieved.
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