In vivo pressure-volume hemodynamics.

At 8 weeks after MI, mice were anesthetized with 4% isoflurane, intubated, and ventilated. A 1.2Fr pressure-volume catheter (Transonic) was inserted via the right carotid artery and advanced into the ascending aorta for blood pressure measurements. The catheter was then advanced into the left ventricle (LV). Real time physiological LV and aortic pressure measurements were recorded on an ADInstrument PowerLab, including LV end-systolic pressure, LV end-diastolic pressure, LV end-systolic volume, LV end-diastolic volume, stroke volume, cardiac output, maximum and minimum first derivatives of LV pressure (dP/dt_max; dP/dt_min), SBP, and DBP. MAP was calculated as DBP + (SBP–DBP)/3. After PV measurements were obtained, the inferior vena cava was briefly occluded to block venous return to determine the end-systolic PV relationship (51). Continuously recorded pressures were analyzed with Lab Chart 7 (Colorado Creeks). A total of 18 mice were used (n = 9 mice/group), with data reported as mean ± SEM.