| Popis: |
Over the past ten years an abundance of transgenic mouse models (gene ablations, overexpressions, or mutations) with variable consequences on heart function have become available. Consequently, quantitative methods had to be developed to analyze cardiac function in the mouse heart. Since the mouse heart is so small (heart weight approximately 125-180 mg) new types of instrumentation for the heart produce new challenges for the cardiovascular and cardiac physiologist. We developed the buffer perfused work-performing mouse heart preparation to analyze myocardial function independent from autonomic or hemodynamic feedback or other compensation. The resultant preparation permits exact control of preload and afterload of the heart. The ejecting heart allows the evaluation of all phases of the intraventricular pressure curve, (systolic, diastolic, and end-diastolic pressure). Furthermore, in order to cover the widest possible range of contractile parameters, ±dP/dt, time to peak pressure (TPP), and 1/2 time to relaxation (RT 1/2) must be recorded. In order to indeed provide reliable quantitative myocardial contractile comparison non-transgenic (NTG) and transgenically (TG) altered littermates have to be directly compared in every case under exactly identical loading conditions. The ideal comparison should be made by the construction of cardiac function curves based upon this pressure and volume loading. |
