The continuing evolution of the Langendorff and ejecting murine heart: new advances in cardiac phenotyping

Abstract

The isolated retrograde-perfused Langendorff heart and the isolated ejecting heart have, over many decades, resulted in fundamental discoveries that form the underpinnings of our current understanding of the biology and physiology of the heart. These two experimental methodologies have proven invaluable in studying pharmacological effects on myocardial function, metabolism, and vascular reactivity and in the investigation of clinically relevant disease states such as ischemia-reperfusion injury, diabetes, obesity, and heart failure. With the advent of the genomics era, the isolated mouse heart preparation has gained prominence as an ex vivo research tool for investigators studying the impact of gene modification in the intact heart. This review summarizes the historical development of the isolated heart and provides a practical guide for the establishment of the Langendorff and ejecting heart preparations with a particular emphasis on the murine heart. In addition, current applications and novel methods of recording cardiovascular parameters in the isolated heart preparation will be discussed. With continued advances in methodological recordings, the isolated mouse heart preparation will remain physiologically relevant for the foreseeable future, serving as an integral bridge between in vitro assays and in vivo approaches.

Fig. 1.

Number of PubMed citations per year, since 1980, that have used an isolated heart preparation (total citations, gray bars). PubMed citations using the mouse heart (black bars) have grown steadily since the late 1990s. The query searched for keywords: isolated perfused heart, Langendorff (some obvious keywords such as lung, liver, kidney, etc., were excluded).

Fig. 2.

Langendorff apparatus: 95% O₂-5% CO₂ tank (A), gas dispersion tube (B), Krebs-Henseleit buffer (KHB) reservoir (C), perfusate line (D), pressure line (E), filter disc (F), compliance chamber (G), balloon (H), erythrocyte perfusate (I), oxygenator (J), and blood filter (K). The KHB reservoir is warmed on a hot plate to 37°C, and the compliance chamber and heart chamber are maintained at 37°C by circulating warm water through the water-jacketed chambers. The heart is electrically paced via platinum electrodes placed on the epicardial surface of the right ventricle. Coronary flow is measured by placing an in-line flow probe in the aortic perfusion line. Coronary perfusion pressure is measured via a sidearm connected to a pressure transducer. Left ventricular (LV) pressure is measured via a balloon inserted in the LV chamber and connected via polyethylene tubing to a pressure transducer. An additional sidearm can be added to the aortic perfusion line for infusion of pharmacological agents. For erythrocyte perfusion, tank A will be a gas mixture of 20% O₂-3% CO₂-77% N₂, and B and C will be replaced by I–K.

Fig. 3.

Ejecting heart apparatus: 95% O₂-5% CO₂ tank (A), gas dispersion tube (B), KHB reservoir (C), recirculation line (D), perfusate line (E), filter disc (F), windkessel (G), atrial reservoir (H), preload line (I), afterload line (J), and overflow reservoir (K). The atrial reservoir, windkessel, and heart chamber are maintained at 37°C by circulating warm water through the water-jacketed chambers. The heart is electrically paced via platinum electrodes placed on the epicardial surface of the right ventricle. Cardiac output is measured by placing an in-line flow probe in the afterload line. Aortic pressure is measured via a sidearm connected to a pressure transducer. An additional in-line flow probe and pressure tranducer sidearm can be placed in the preload line to measure atrial flow rate and atrial pressure. LV pressures and volumes can be simultaneously measured via a 1.4-Fr high-fidelity transducer inserted into the apex of the LV and sutured. Cardiac preload and afterload can be adjusted by varying the heights of the atrial reservoir and overflow reservoir.

Fig. 4.

A: isolated isovolumically contracting mouse heart erythrocyte perfused in the Langendorff mode. The aorta was cannulated with a 20-gauge (G) blunt-ended needle (right of picture). A balloon was inserted into the LV and connected via tubing (middle of picture) to a pressure transducer. The pulmonary artery was cannulated with polyethylene tubing (blood-filled tubing, left of picture) to collect the coronary effluent. B: isolated mouse ejecting heart with crystalloid perfusion (the LV was infarcted as evidenced by the whitish pallor of the lower portion of the heart). The aorta was cannulated with an 18-G blunt-ended steel needle (center of picture); a custom-made water-jacketed windkessel can be seen just above the aortic cannula. The preload line including 18-G atrial cannula is shown to the left of the picture; the preload line is attached to a ball-and-socket joint to allow freedom of movement in all planes. Shown to the right of the picture are two epicardial pacing wires held in place with ball-and-socket joints.