when I first met you,

baby.

You fed me on chicken and wine.

It was steak and potatoes and lobster 

and baby.

I sure felt fine.

This program was designed to supplement lectures on 

gastrointestinal physiology.

The format of this program is part laboratory 

demonstration and part discussion.

This format has been selected to maximize the impact of 

this information by providing the student with actual 

laboratory data and subsequently discussing this 

data.

To provide a perspective for understanding G.I

Motility.

After completing this program,

you should be able to one describe the 

occurrence of a frequency gradient within the small 

intestine of the G.

I tract to describe the 

occurrence of higher frequencies in the proximal portion of 

the small intestine.

Three explain the translation of the 

frequency gradient into a pressure gradient 

and four described the sodium dependence of the 

basic electrical rhythm.

Five described the calcium dependence 

of smooth muscle,

contract ill itty.

The purpose of this program is to demonstrate 

gastrointestinal motility.

We're going to do this in a laboratory setting.

Obviously we can't use human tissue to demonstrate 

this.

And the closest laboratory animal that 

can resemble the gastrointestinal 

motility of humans is that of the rat.

We will be showing you the frequency 

gradient that occurs in the longitudinal 

muscle from the small intestine.

We will be showing you the frequency gradient that 

occurs within that muscle from 

the duodenum to the ilium 

and that frequency gradient will then be translated into a pressure 

gradient.

Right now,

I'd like to have dr Weissinger explain her experimental 

protocol.

The rat was sacrificed by decapitation.

The entire small intestine was removed.

Four sections of the small intestine were separated from the rest 

of the small intestine,

the proximal duodenum,

the proximal proximal ilium 

and distal ilium.

The longitudinal smooth muscle,

which is the outer layer of the gut was teased 

away from the other section of the small 

intestine.

This smooth muscle was hooked up in a smooth 

muscle bath And immersed 

in the physiologic buffer.

The physiologic buffer contains physiologic concentrations of 

sodium potassium,

calcium,

magnesium dextrous is an energy source and 

is bubbled with 100% oxygen.

The smooth muscle is hooked up to a forced displacement 

transducer,

which is in turn connected to a dyno graph 

recorder.

The isometric 

contraction produced by an 

agonist will in turn be recorded on the 

dyno graph as a change intention,

which will be shown by a pen deflection.

The tracings produced by all depends on the fizzy.

A graph represent the spontaneous activity of each of the 

sections of the small intestine which we have 

removed.

The first pen shows the spontaneous 

activity in the duodenum,

the second,

the spontaneous activity in the home and the 

third in the ilium and the fourth,

the terminal ilium.

As you can see the activity in the 

duodenum is much greater.

The frequency of contractions is much greater in the duodenum than 

it is in the terminal ilium and there is a gradual 

transition in the rate at which the 

longitudinal muscle contracts going from the duodenum 

to the terminal ilium.

We are now going to add acetylcholine to each of the 

baths.

Acetyl colon being the normal neurotransmitter 

substance for the parasympathetic outflow 

which innovates the gut.

Acetylcholine will produce a rapid 

phase IQ increase intention 

followed by a more 

prolonged tonic contraction.

Dr Y singer will now add acetylcholine to each of the 

tissue baths 

first I'll add it to the terminal ilium now 

to the ilium.

Then I'll add to the junior 

and eduardo.

The acetylcholine will now be washed out of each of the tissue 

baths and the tissue will now go 

into a relaxation.

The normal physiological buffer will be replaced with a 

sodium free buffer with the sodium has been 

replaced with an isotonic or rather its 

osmotic concentration of sucrose.

It will take approximately 30 minutes for the tissue to 

equal a break with this new solution during this 

time the cameras will not be running to 

expedite this film.

In this second part of our program we're going to see the 

effects of a sodium free solution on the spontaneous 

activity in the smooth muscle.

From the small intestine.

As you can see from the tracing that there is very little 

spontaneous or no spontaneous act 

activity in any of the smooth muscle sections 

from the small intestine.

This demonstration is to show that sodium 

is a very important ion for 

maintaining the spontaneous activity in the small 

bowel.

We are going to demonstrate however,

by the addition of acetylcholine that 

acetylcholine is still capable of inducing 

a contraction of these smooth muscle 

preparations dr Weissinger will 

now add acetylcholine to each of these 

preparations.

Acetylcholine has now been added to the terminal alien 

portion of these tissues.

And you can see that there is a rapid increase in 

tension,

occurring.

The maximum tension achieved in each of these 

preparations is going to be smaller than 

that which we observed in the previous portion of this 

program.

The point that we're trying to make is that acetylcholine is 

still capable of producing a contraction in these 

tissues.

Even though the sodium ion has been removed from the 

physiological medium.

The contractor responses to acetylcholine have now 

plateaus.

And we're going to wash the solution out,

wash the acetylcholine out with a solution 

which has normal physiological levels of 

sodium potassium,

magnesium dextrose.

But no calcium.

In the third part of this film we will be 

observing what the effect of a 

normal physiological solution is without 

calcium.

In this third part of the program,

we're going to see what acetylcholine will do in 

these particular tissues.

Uh they've been incubated with zero calcium 

physiological solution for 

approximately 45 minutes.

Now,

as you can see from the tracings,

there are no spontaneous activities and any other 

portions of the small intestine that we have 

taken from the rat.

If you remember in the previous section when we added 

acetylcholine to the relatively quiescent 

smooth muscle as we have here,

we got a rather large contraction of the smooth 

muscle.

We're now adding the acetylcholine to the tissues 

that have been equal abraded in the zero calcium 

medium.

As you can see there is no spontaneous activity in these 

tissues.

And when we add acetylcholine to these preparations,

we should see no response 

in the previous section of this program.

We saw that as still Killeen when added to the sodium free 

solution which also was quiescent,

we got a rather substantial contraction of the 

tissues.

However,

in zero calcium we see that there is no response to 

acetylcholine.

We are now going to wash the tissue free of 

acetylcholine and replace the 

calcium free medium with normal 

physiological buffer.

By replenishing both the sodium and 

the calcium back into the tissue.

We should be able to re establish a spontaneous 

activity as well as uh 

contract the ability of the tissues in the 

presence of acetylcholine.

We will see these phenomenon in our 

fourth portion of the program 

We will allow approximately 

30-45 minutes for the tissues to equal a break.

Before we begin the fourth part of the program 

In this fourth part of our program,

the tissues have been equal abating for 15 minutes now.

In normal physiological solution containing 

sodium potassium calcium and 

magnesium.

As you can see the tissues are responding in a normal 

way as they have in the part one of this 

program,

the frequency gradient is again 

established between the duodenum and the terminal ilium 

dr Y.

Singer is now going to add acetylcholine to each of the 

tissues to confirm that they are still 

capable of producing a 

contraction in these particular 

tissues.

As you can see,

the acetylcholine produced very nice contractions.

Similar to what we had in the first 

part of this program.

We are now going to go down to the studio 

where we will have our fifth part of this program,

which will be a summary of all the 

data that we have presented so far.

In this fifth portion of our program,

we're going to review the sections that we have already covered.

We're going to look at the data and relate the 

contract of events which occurred to the 

ionic constituents of the medium in which the smooth 

muscle was bathed.

On this first plate.

The bottom tracing represents the tracing that 

the muscle contractions that occurred in the 

duodenum,

in the in the mid ilium and in the 

terminal ilium.

And we can see that there is a frequency gradient from the 

duodenum to the terminal ilium.

The duodenum contracts at a much rapid,

much more rapid rate than does the terminal 

ilium and therefore we have a frequency 

gradient which occurs from the most proximal 

to the distal portion of the small bowel 

on the next plate.

This shows what happened when we added acetylcholine 

to each of the segments of the small bowel that 

we had been observing 

acetylcholine was added to the duodenum to 

june,

um midday liam and terminal 

ilium.

And you can see that acetylcholine caused a 

rather substantial contraction in each of these segments of the 

smooth muscle from the small intestine.

This just shows that the smooth muscle will 

respond to the normal neurotransmitter substance 

acetylcholine.

At the end of this contraction,

the tissue was washed with sodium free 

solution.

The solution did not contain sodium but contained 

an isotonic or so 

osmotic concentration of sucrose.

When the sodium was replaced 

we found that rhythmic contractions in all 

sections of the small bowel no longer occurred.

Yet the smooth muscle in each of those 

sections was capable of responding 

to added acetylcholine to each of the 

baths.

The implication here is that the removal of sodium 

somehow causes a loss in the spontaneous 

activity.

However,

the ability of the smooth muscle in each section is still 

capable of responding to added 

acetylcholine,

the normal neural transmitter which produces contraction 

in the small bowel.

At the end of this particular experiment we 

replaced the sodium free solution 

with solution which contains sodium but did not 

contain calcium in 

this next plate.

You can see that the result of 

leaving out the calcium from the physiological 

solution results in flat tracings 

a loss of all spontaneous activity.

When acetylcholine was added at approximately this point 

in the tracing there was no increase 

in tension.

So the removal of calcium.

Therefore not only eliminates the spontaneous 

activity but also eliminates the 

responsiveness to the normal neurotransmitter substance.

Acetylcholine.

After this portion of the experiment was done,

the tissue was washed again with normal 

physiological solution.

After approximately 30 to 40 minutes,

spontaneous activity began occurring again.

And we could see that the frequency gradient has been 

reestablished.

The duodenum is contracting 

much more rapidly than the terminal ilium.

So we see this frequency gradient.

The reason that we did put the 

tissues back into normal physiological medium 

was to show that the tissues were not killed or altered 

in any prolonged way,

that the lack of spontaneous activity was 

merely due to a change in the ionic constituents 

within the physiological medium.

Again,

when acetylcholine was added in this normal 

physiological solution,

contractions occurred in a 

way which was similar to that which we had 

seen in section one of this program.

At this point,

I'd like to summarize the implications of all these 

ionic variations which we performed in 

sections one through four.

When we removed the sodium from the 

physiological medium,

we lost spontaneous activity.

However,

the responsiveness to acetylcholine was still 

retained.

The implication there is that the ability of 

the smooth muscle to contract was 

retained when we 

change the tissues to a calcium free 

medium.

Not only did we lose the spontaneous activity,

but we also lost the ability to respond to 

acetylcholine.

We can extrapolate this data one bit 

further and we know that there is an electrical 

fluctuation in membrane potential 

within each of the sections of the smooth muscle of 

the small bowel.

This fluctuation is called the basic electrical rhythm.

This basic electrical rhythm is a sodium dependent 

phenomenon.

If we remove the sodium the spontaneous 

activity which occurs at a frequency dictated 

by the basic electrical rhythm,

this spontaneous activity is removed when sodium is 

removed.

When we remove calcium,

not only do we remove the contra activity that the 

basic electrical rhythm dictates,

but we also remove the contra activity which occurs 

when the neurotransmitter substance.

Acetylcholine is put in 

contact with the smooth muscle,

therefore contract ill.

Itty is direct directly related 

to the presence of calcium 

and the basic electrical rhythm is directly 

related to the presence of sodium in the physiological 

medium.

Our next chart 

demonstrates that a little more clearly 

on the lower portion of this diagram we see a 

fluctuating line which 

represents the fluctuation 

occurring in the membrane potential.

This fluctuation is called the basic electrical 

rhythm or the B.

Er.

This be er or the frequency of the B.

E.

R.

Varies according to its location 

within the small bowel.

We can consider a threshold occurring 

anywhere along this.

Be er If the 

B.

E.

R exceeds this 

threshold we will be able to get 

action potentials occurring.

These action potentials in smooth muscle are calcium 

dependent after the 

occurrence of an action potential.

We see that there is an increase in tension which is 

what the upper tracing represents.

So you can see that the primary event is an action 

potential superimposed on the basic electrical rhythm 

followed by an increment intention.

If the basic electrical rhythm does not exceed a 

threshold,

action potentials will not occur.

If this threshold is below the level 

exceeded by the basic electrical rhythm,

we will get action potentials.

The basic electrical rhythm is sodium dependent action 

potentials and contract illit E.

R.

Calcium dependent on the 

next plate.

We see what happens when we record the 

action potentials in a single smooth muscle cell 

by intracellular micro electrodes.

This is an action potential which occurs in a 

single smooth muscle cell.

After the action potential occurs,

we see a rather rapid increase 

in tension followed by a rather slow decay in 

the tension.

The slow decay is due to the stickiness of the 

contractor elements in smooth muscle.

When we have action potentials occurring in rapid 

sequence or relatively rapid sequence,

the tension which occurs is additive in nature.

As you can see the tension some 

mates as a result of each of these 

action potentials,

depending upon how much the basic electrical rhythm 

exceeds the threshold value will determine 

how many action potentials occur.

How many action potentials determines the 

extent of the contraction.

This next figure relates 

directly to the tension development in 

isolated human colonic muscle with the 

electrical activity in that smooth muscle.

This is an extra cellular recording and each of these up 

and down spikes represents one 

or possibly more action potentials.

You can see that in this small grouping of action 

potentials.

We get relatively little 

contraction.

In this grouping of large 

numbers of action potentials.

You can see that we get a summation of a great 

and a prolonged contraction.

I would like to relate this information now 

to the pressure gradient which is the 

translation of the frequency gradient throughout 

the small bowel.

If you look at the pressure 

increment or tension increment that occurs during this period 

of high action potential activity 

and we conceive of a number of these 

activity areas occurring frequently,

one after the other.

This can be visualized as 

producing a higher pressure than 

in section of the small bowel where 

these tension increments occur at a less 

frequent time interval.

Therefore the frequency gradient dictated 

by the basic electrical rhythm is translated 

into a pressure gradient.

At this point in the program,

you should have a better understanding for the controlling factors 

and gastrointestinal motility.

You should have a feeling for.

What does the B.

E.

R.

Mean?

And how does this relate to the frequency gradient which 

occurs in the small bowel?

How does the frequency gradient translate itself 

into a pressure gradient?

And what are the controlling factors 

involved in smooth muscle contraction?

The fact that sodium is responsible for the basic 

electrical rhythm and that calcium is responsible 

for smooth muscle contract ill itty 

I'm going down to the bakery and I'm gonna find 

me a jelly roll 

and some cannoli,

some french pastry,

a chocolate eclair.

Don't sound too bad.