ADInstruments Research Product Manager, JC Tan, talks to us about the Direct Perfusion Core - a unique component of the new ADInstruments Rodent Langendorff Apparatus.
The Direct Perfusion Core is central to the Langendorff design and attaches above the Heart Chamber. It combines many powerful features into one component. With locking luer inlet and outlet ports, using Radnoti’s leak-tight design, researchers can control the flow of liquid in the apparatus. This component has a built-in compliance chamber connected to a syringe port to trap any bubbles in the perfusate for removal with a 20 mL Damping syringe.
JC’s favorite features of the Direct Perfusion Core include:
- The capacity to collect data from closer to the heart with four side ports for sensors
- Using recirculation to prevent the perfusate from degassing during the experiment setup
- The optimization of the perfusate pathway to reduce any delay in delivering perfusate to the heart
- The inner glass spiral, designed to minimize temperature loss in the perfusate
Related Article: Why we redesigned the Langendorff Apparatus »
Data directly from the heart
The Direct Perfusion Core’s key feature is its four sensor ports, positioned to allow data measurement to be made closer to the heart. As a result, the apparatus design would improve user data accuracy and reduce signal damping and noise due to distance.
“What would a researcher be trying to measure? They would be interested in the inherent physiological cardiovascular parameters of the heart. However, often those measurements are placed quite far from the heart in commercial options.”
Each sensor port can be attached to a number of interfacing options: a watertight luer port coupler, a rubber port coupler, and a rubber septa to transform it into an injection port. These options enable researchers to record many data types, depending on the attaching sensor.
“With four sensor ports, you can insert various sensors to collect measurements just before the perfusate goes to the heart. Additionally, there is the option to put a three-way tap between the perfusion core and the heart to have an even more direct measurement if needed.”
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Prevent degassing with recirculation
The surgical removal of the heart is one of the most taxing and time-critical elements of working heart applications. After removal from cardiac circulation, the heart should be cannulated within three minutes. Efficient cannulation will prevent the heart tissue from degrading and drying out. Most researchers, therefore, prepare their Langendorff apparatus before surgery - or in conjunction if they have assistance.
During experimental preparation, the Langendorff apparatus will be primed with perfusate, waiting for the heart to be cannulated, before beginning the perfusion. If the perfusate sits idle within the Langendorff apparatus circuit, it will begin to degas - a process by which oxygen leaves the solution, altering the perfusate's pH and suitability.
The Direct Perfusion Core allows the user to recirculate the perfusate while the apparatus is in standby mode to maintain perfusate suitability.
“There is no stress for the user regarding timing, thinking that the perfusate is going to degas while they are focusing on their surgery. Using a three-way tap, you can reconnect the perfusion pathway to the reservoir, allowing for the perfusate to return to be regassed.”
By recirculating the perfusate through the Langendorff Apparatus, fresh perfusate from the reservoir will always be available. Researchers can keep their attention where it needs to be during setup and prevent undesired changes in the perfusate from impacting data quality.
Accurate and quick perfusate delivery
For many pharmacology studies, where the perfusate is infused with drugs to improve heart function, it is important to be precise.
“In an ischemic reperfusion study, where you stop perfusion and want to restart the heart, your design might want to stop perfusion for five minutes. When you want to reintroduce the perfusate with the drugs, the time it takes to get to the heart is longer than what you thought it was if you were perfusing it from another reservoir.”
“I noticed that in a lot of classical Langendorff designs, it takes a long time for the perfusate to flow from the reservoir to the heart. I wanted to design a way to reduce that time so that effectively if I start the peristaltic pump, I know it will reach the heart within a certain time.”
Delay or inconsistency in perfusate delivery could affect the effectiveness of pharmacological interventions. JC designed the Direct Perfusion Core to deliver accurate and quick perfusion, reaching the heart in one to two minutes for a mouse model. Giving researchers more control over the timing of perfusate delivery enables the precision necessary for these applications.
Temperature control
To maintain the optimal perfusate temperature, the Direct Perfusion Core contains a heat exchanger. A coil of high-quality borosilicate glass compensates for any heat loss in the perfusate pathway.
“We've done several designs and leveraged the experience from Radnoti in understanding flow rate and temperature, to ensure that the temperature is maintained,” JC says. “Additionally, the length of the perfusate line from the reservoir to the Perfusion Core was optimized, so the heat exchanger mitigates any temperature loss before it reaches the heart.”
Final comments
“I wish I had had the whole PowerLab system when I was studying. There is definitely a huge difference to the lab-built system I was using. I packed a lot of powerful features into the apparatus. Once you start thinking of how you want to evolve it in the future, it will be quite easy to do so.”
ADInstruments is dedicated to making science easier and innovating the technology researchers rely on. The ADInstruments Rodent Langendorff Apparatus is our modular yet compact solution, ideal for retrograde perfusion of isolated rodent hearts (mice, rats, guinea pigs, and small rabbits).
Our support team is passionate about research. Please contact your local representative if you have any questions about how to customize our products to fit your application.
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Dr. JC Tan completed his Ph.D. in Sydney, Australia, at the Graduate School of Biomedical Engineering of the University of New South Wales in conjunction with Victor Chang Cardiac Research Institute. He is currently a Research Product Manager with ADInstruments.
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PowerLab C Rodent Langendorff Foundation System »
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Radnoti Langendorff Systems (Constant Pressure or Flow) »