Langendorff System Cleaning Guidelines

General Cleaning Guidelines

It is essential to maintain the Langendorff system in a clean condition as the physiological perfusate

solutions support bacterial and fungal growth which can affect the heart preparation. Daily and

fortnightly cleaning protocols are described below. Adequate maintenance will prolong the life of your

equipment.

Use a germicide

To minimize the growth of algae and microorganisms in the waterbath and tubing of the heating system,

always use deionized (or distilled) water. A cationic surfactant and germicide can be used to keep the

water bath free of bacterial and algal growth. ‘Sigmaclean’ water bath treatment (Product Number

S5525, CAS Number: 68424-85-1), from Sigma, used at a dose of 0.16 mL/L or 0.02 oz/gal., is

suitable.

This should keep the heating system clean between the fortnightly cleaning protocol, however,

if slight turbidity in the waterbath is observed, then drain and refill the waterbath with dilute domestic

bleach (sodium hypochlorite solution) — use about 25 mL of 4% bleach per liter of water. Allow to stand

for about 10 minutes, then drain and rinse with deionized water, and then refill with fresh deionized

water containing the germicide.

Do not autoclave

Note that the Langendorff apparatus is mainly constructed of Perspex (or acrylic). Under no circumstances

should the system be autoclaved.

Do not use boiling water

Boiling water may soften and distort the Perspex of the Langendorff apparatus. Do not use water hotter

than 80 °C when cleaning the system.

Do not use organic solvents

Do not use alcohol, or other organic solvent based cleaning agents, as these can damage the Perspex

surfaces.

Do not use abrasives

Avoid the use of all abrasive pastes and scourers such as steel wool. These will damage the Perspex

surfaces and perfusate reservoirs and make future cleaning more difficult.

Do not use aggressive chemicals

Aggressive chemicals, such as concentrated hydrochloric acid, sulfuric acid and sodium hydroxide can

damage the system and should never be used.

Langendorff For Internal Use Only 7 ADInstruments Primer Document For Internal Use Only

Regular Procedures:

Daily cleaning protocol

After daily use the perfusion system, junction block and heart chamber should be cleaned (the waterbath

need not be emptied to do this):

1. Keep a slow gas stream passing through the bubblers to prevent solution from entering the gas

lines.

2. Remove all perfusate solution from the system and flush the perfusate reservoirs and connection

tubes with deionized water. If necessary, flush with hot (65–80 °C) water, to dislodge any biological

material. Higher temperatures may damage the surface of the Perspex reservoirs.

3. Fill the perfusion system with 1 mol/L ascorbic acid solution and leave in the system overnight.

4. Next morning, remove the ascorbic acid solution (the ascorbic acid may be used 6-8 times) then purge

the system thoroughly with deionized (or distilled) water.

5. Refill the reservoirs with perfusate solution for the new experiment.

Fortnightly cleaning protocol

This protocol should be followed every two weeks, or before long term storage.

Perfusate reservoirs and waterbath

Clean as follows:

1. Before cleaning, all connection tubing should be disassembled, and the waterbath and perfusate

reservoirs should be emptied. Ensure that the bubbling regulators for each perfusate reservoir have

been closed.

2. Use a soft nylon brush and a mild detergent solution (non-foaming, if possible) to clean inside

the perfusate reservoirs, waterbath, junction block and heart chamber. Drain and then rinse with

deionized water.

3. If there are still persistent algal stains, fill the reservoirs and waterbath with diluted household bleach

(sodium hypochlorite solution). Use about 25 mL of 4% bleach solution in about 1 L of water. Allow

to stand for 10 minutes. Drain and flush with large quantities of tap water. Repeat step 2.

4. Check that the bubbling system still works.

5. If the system is to be stored, allow all parts to dry thoroughly.

Heart chamber and Junction Block

In cases of severe soiling, disconnect the glass heart chamber or junction block from the system and

immerse it in full strength domestic bleach solution (4% available chlorine) and leave overnight. After a

thorough cleaning with detergent solution, tap water and deionized water, reconnect the heart chamber

to the system. Never use full strength bleach to clean tubing or Perspex surfaces.