In a Langendorff experiment an isolated heart is maintained in an organ bath while the coronary arteries are perfused with a buffered, oxygenated, nutrient solution. The experiment can be done under conditions of constant perfusate flow or pressure, and the heart can be paced by an external stimulator.

The perfusate does not flow into the heart in the same manner as blood in a whole animal. Instead, the aorta is cannulated and the solution is delivered in a retrograde fashion down the aorta. The perfusate does not enter the heart chambers themselves, but flows through the coronary vascular system, which supplies the heart muscle with nutrients required for contraction. 

Parts of the System:

Circuit of Perfusate:

We have two water-heated perfusate reservoirs in which we can have two different nutrient solutions (perfusates). These reservoirs are constantly oxygenated and kept at a constant bath temperature.

The solutions are pumped from the bath by a peristaltic pump, through a jacketed warming coil and into the aortic block. The aortic block contains the cannulated heart. Two solutions can be circulated, but only one is used at any given time. The other will be recirculated. This allows the user to switch solutions during an experiment.

The heart is canulated at the "heart block" (item D in the above photo) otherwise called the aortic block. The aortic block is where experimental measurements for perfusion pressure and temperature can be assessed. 

Oxygenation:

Oxygenation is controlled by bubbling oxygen into the perfusates. Oxygen pressure should be supplied by an oxygen tank and the regulator should be set to 0.5bar.

Maintenance of the thermojacketed equipment:

To control for the growth of fungus and algae inside of your system we recommend the use of a fungicide. 

For more information on cleaning and maintenance please visit this article. 

Thermoregulated reservoir

Fill the glassware to a level where the water level sensor (blue float, item G) and the perfusate reservoirs are covered (item A). Note-the blue float should always remain wet. If the float dries there is an emergency cut off to the heating system. 

Please use only distilled water to fill your reservoir. The liquid in this reservoir will be circulated using a magnetic pump and can be emptied using the drain key (item L). This warmed fluid is used to keep all jacketed glassware temperature controlled. Such as item J heated jacket for heart.  

How to Start:

• Before beginning please inspect your equipment. 
• Fill both perfusate reservoirs (A in image above)
• Connect the oxygen to the gas inlets (I in the image above)
• Fill the outer reservoir with distilled water + fungicide
• Set the temperature see Setting Temp below.
• Set the flow rate of the peristaltic pump or if working with constant pressure set up appropriately for PID control.
• Wait until system reaches desired oxygenation levels and temperature.
• The last step is to cannulate your heart and hang it (item D and J in image above).

Your system is supplied with 2 cannulae.

• 2.1mm OD, 30mm length
• 0.7mm OD, 30mm length

Setting Temperature (LE13206)

Front:

Back:

The thermostat unit LE13206 controls the temperature of the water inside of the Panlab Langendorff system. The temperature range is room temperature up to 45°C. The system will heat the "heating rod" labeled item F above. The temperature is constantly monitored and displayed on the LE13206. There is a safety thermostat (item M in the image above) that can shut down the heating to the rod in the event of an emergency (such as an empty reservoir). 

The temperature adjustment is located at the back of the system and used to finely tune the bath temperature, but only when the heating system is off. To increase the temperature turn clockwise very slowly allowing time for the water bath to respond. The heating rod is designed to efficiently heat the bath of your Langendorff system and works on a feedback loop to regulate the power to the heating rod. As the system approaches the set temperature the amount of current supplied to the heating rod decreases. Overall the system can maintain a temperature close to 0.1 degrees to your set temperature. 

You will not see any water movement from the magnetic pump and very little vibrations are introduced with this type of water movement system. 

NOTE: The water must never exceed 45°C otherwise you may damage your system.

How to Operate:

• Be sure system is filled
• Push the On/Off switch on the Thermostat Unit to On.
• The LEVEL LED will light when the level of the water is the correct level to start your experiment. Prior to the LEVEL LED lighting no power is supplied to the heating rod.
• Press TEMPERATURE SELECTOR, and use the up/down arrows to set your target temperature (between 25°C and 45°C). If you do not select a temperature within the first 15 seconds the system will begin heating on its own.
• Push the TEMPERATURE SELECTOR button a 2nd time and this sets your temperature. Once the target temperature is reached the HEAT LED will go out. 
• Once the system stabilizes, and the set temperature is achieved and overall maintained the display will show "-------"

Maintenance

In order to keep your system working for a long time it is necessary to keep it well maintained. You will need to clean the perfusate circuits regularly and clean the container when necessary. Do not use abrasive substances. Most pieces of the system can be easily removed for cleaning.

Once emptied:

Make sure that the bubbling regulator is closed. Rub the inside of each reservoir with a soft brush soaked in soapy (but not foaming) water.

Use a mild acid solution (0.25% sulfuric acid or 0.1N Hydrochloric acid) into the vessels and pipes, leaving it to rest for 30 seconds before rinsing with a large volume of water.

Finally rinse all equipment with distilled water.

NOTE: Never use alcohol based products to clean plastic parts! This will crack these parts causing failures. 

Removing and changing pieces:

Needle valve:

Take the needle-valve changer tool . using the part with the cleft in it catch the needle-valve and pull it gently out.