The Langendorff heart or isolated perfused heart assay is an ''

ex vivo ''Ex vivo'' (Latin: "out of the living") literally means that which takes place outside an organism. In science, ''ex vivo'' refers to experimentation or measurements done in or on tissue from an organism in an external environment with minimal ...

'' technique used in pharmacological and physiological research using animals and also humans. It allows the examination of cardiac contractile strength and

heart rate Heart rate (or pulse rate) is the frequency of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm). The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and excr ...

without the complications of an intact animal or human. After 90 years this method is still being used.

Method

In the Langendorff preparation, the

heart The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide t ...

is removed from the animal's or human's body, severing the

blood vessel The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away ...

s; it is then perfused in a reverse fashion ( retrograde perfusion) via the

aorta The aorta ( ) is the main and largest artery in the human body, originating from the left ventricle of the heart and extending down to the abdomen, where it splits into two smaller arteries (the common iliac arteries). The aorta distributes ...

, usually with a nutrient rich, oxygenated solution (e.g.

Krebs–Henseleit solution Krebs–Henseleit solution, developed by Hans Krebs and Kurt Henseleit, is a solution containing sodium (Na), potassium (K), chloride (Cl), calcium (Ca), magnesium sulfate (MgSO4), bicarbonate (HCO3), phosphate (PO4), glucose, and sometimes supplem ...

or Tyrode's solution). The backwards pressure causes the

aortic valve The aortic valve is a valve in the heart of humans and most other animals, located between the left ventricle and the aorta. It is one of the four valves of the heart and one of the two semilunar valves, the other being the pulmonary valve. The ...

to shut, forcing the solution into the coronary vessels, which normally supply the heart tissue with blood. This feeds nutrients and oxygen to the cardiac muscle, allowing it to continue beating for several hours after its removal from the animal or human. This is a useful preparation because it allows the addition of drugs (via the perfusate) and observation of their effect on the heart without the complications involved with ''in vivo'' experimentation, such as neuronal and hormonal effects from living animal or human. This preparation also allows the organ to be digested into individual cells by adding

collagenase Collagenases are enzymes that break the peptide bonds in collagen. They assist in destroying extracellular structures in the pathogenesis of bacteria such as ''Clostridium''. They are considered a virulence factor, facilitating the spread of ...

to the perfusate. This can be done before the experiment as a technique for cell harvesting, or after the experiment to measure its effects at the cellular level.

History

The first isolated perfused heart was created using frog tissue in 1866. Four decades later, the most famous pioneer of this technique, Oscar Langendorff, then developed a model where mammalian hearts could be completely isolated ''ex vivo''. This variation of the technique, known as the "Langendorff Heart" was later converted into the working model in 1960 by Howard Morgan and James Neely.

References

External links

Isolated heart in preclinical studies
Animal testing Measuring instruments {{circulatory-stub

Method

History

See also

References

External links