Cardiac and coronary function in the Langendorff‐perfused mouse heart model

Abstract

The Langendorff mouse heart model is widely employed in studies of myocardial function and responses to injury (e.g. ischaemia). Nonetheless, marked variability exists in its preparation and functional properties. We examined the impact of early growth (8, 16, 20 and 24 weeks), sex, perfusion fluid [Ca 2+ ] and pacing rate on contractile function and responses to 20 min ischaemia followed by 45 min reperfusion. We also assessed the impact of strain, and tested the utility of the model in studying coronary function. Under normoxic conditions, hearts from 8-week-old male C57BL/6 mice (2 mm free perfusate [Ca 2+ ], 420 beats min -1 ) exhibited 145 ± 2 mmHg left ventricular developed pressure (LVDP). Force development declined by ∼15% (126 ± 5 mmHg) with a reduction in free [Ca 2+ ] to 1.35 mm, and by 25% (108 ± 3 mmHg) with increased pacing to 600 beats min -1 . While elevated heart rate failed to modify ischaemic outcome, the lower [Ca 2+ ] significantly improved contractile recovery (by >30%). We detected minimal sex-dependent differences in normoxic function between 8 and 24 weeks, although age modified contractile function in males (increased LVDP at 24 versus 8 weeks) but not females. Both male and female hearts exhibited age-related reductions in ischaemic tolerance, with a significant decline in recovery evident at 16 weeks in males and later, at 20-24 weeks, in females (versus recoveries in hearts at 8 weeks). Strain also modified tolerance to ischaemia, with similar responses in hearts from C57BL/6, 129/sv, Quackenbush Swiss and FVBN mice, but substantially greater tolerance in BALB/c hearts. In terms of vascular function, baseline coronary flow (20-25 ml min −1 g −1 ) was 50-60% of maximally dilated flows, and coronary reactive and functional hyperaemic responses were pronounced (up to 4-fold elevations in flow in hearts lacking ventricular balloons). These data indicate that attention to age (and sex) of mice will reduce variability in contractile function and ischaemic responses. Even small differences in perfusion fluid [Ca 2+ ] also significantly modify tolerance to ischaemia (whereas modest shifts in heart rate do not impact). Ischaemic responses are additionally strain dependent, with BALB/c hearts displaying greatest intrinsic tolerance. Finally, the model is applicable to the study of vascular reactivity, providing large responses and excellent reproducibility.

Langendorff's isolated perfused rat heart technique: a review

“…However, blood has few disadvantages as a perfusion fluid as it can undergo progressive hemolysis during the perfusion and such perfusion solutions are more difficult and time-consuming to prepare. [8][9][10][11] Washed erythrocyte perfusion solutions are found to be similar to those for the blood perfused preparation which uses a support animal. It enhances the stability when compared to crystalloid perfused hearts, with pressure development remaining stable for extended periods of perfusion.…”

“…An alternative to anesthesia is cervical dislocation or concussion, but in both instances, there are major effects on catecholamine's and other circulating factors, so these are not recommended. [8][9][10]14,15 Procedure After surgical anesthesia, careful excision of aorta and cannulation are the first steps done. A set of sutures and instruments positioned close at hand and rat is placed in a dissecting tray near the isolated heart apparatus.…”

Intravenous Adeno-Associated Virus Serotype 8 Encoding Urocortin-2 Provides Sustained Augmentation of Left Ventricular Function in Mice

“…Cardiac function was investigated in isolated perfused hearts to assess LV contractile function in a manner unaffected by reflex activation or anesthesia, as previously reported (Reichelt et al, 2009;Roth et al, 2002). An intraventricular balloon catheter was deployed to measure isovolumetric LV pressure (LV end-diastolic pressure, 10 mmHg; 2.5 mM CaCl 2 ).…”

Transcriptomic effects of adenosine 2A receptor deletion in healthy and endotoxemic murine myocardium

“…Additionally, there is an apparent coronary 'over-supply' relative to myocardial demand in endotoxemic hearts (Table 1), owing to 25-30 % lower contractile function without reductions in coronary perfusion. The absence of coronary coupling to ventricular activity, described by us in this and other models [95,96], suggests additional coronary dysregulation (though this effect is neither replicated nor modified by A 2A R KO). Multiple paths/mediators regulating angiogenesis were also sensitive to A 2A R KO in endotoxemic heart, including shifts in VEGF, HIF-1α, angiopoietin, TGF-β, GM-CSF, PDGF and IGF-1 pathways (Table S10) and key regulatory molecules (including exaggerated induction of Il6, Pgf, Tgfb2, Tgfb2r, Angptl4 and Amotl1; exaggerated suppression of Vegfc and reduced suppression of Qk) (Table S9).…”