Mpvs ultra

Hemodynamic measurements were performed at the 8-week endpoint, prior to euthanasia. Rats were anesthetized and ventilated as described previously. After thoracotomy without bleeding, the LV apex of the heart was punctured with a 26 G needle, and a 2 F conductance catheter (SPR-838, Millar) was inserted into the LV. LV pressure–volume parameters were continually recorded using a PV conductance system (MPVS Ultra, emka TECHNOLOGIES, Paris, France) coupled to a digital converter (PowerLab 16/35, ADInstruments, Colorado Springs, CO). Load-independent parameters of cardiac function, including the slopes of the end-systolic pressure–volume relationship (ESPVR) and end-diastolic pressure–volume relationship (EDPVR), were measured at different preloads, which were elicited by transient occlusion of the inferior vena cava with a needle holder. Fifty microliters of hypertonic saline (20% NaCl) was injected into the left jugular vein to calculate the parallel conductance after hemodynamic measurements. Blood was collected from the left ventricle into a heparinized syringe and transferred into cuvettes to convert the conductance signal to volume using the catheter. The absolute volume of the rat was defined by calibrating the parallel conductance and the cuvette conductance.

Pressure–volume loop analysis was performed in mice according to the method described previously^{22 (link)}. A microtip 1.4 F catheter (SPR-839, Millar Instruments, Houston, TX) was inserted into the right carotid artery of mice. The arterial pressure was recorded and the catheter was advanced to LV guided by pressure tracing. The signals of pressure and volume were continually recorded by using a conductance system (MPVS Ultra, emka TECHNOLOGIES, Paris, France) coupled to a digital converter (ML-870, AD Instruments, Colorado Springs, CO). LVEF was derived from the pressure–volume diagram.

For hemodynamic evaluations, rats were subjected to anesthesia via intraperitoneal administration of thiopental sodium at dosages ranging from 60 to 80 mg/kg. Subsequent to anesthesia, a surgical incision was made to expose the right carotid artery, facilitating the insertion of a 2.0 F microtip pressure–volume (PV) catheter (Model SPR-838, Millar Instruments, Houston, TX, USA). Following initial arterial pressure recording, the catheter was carefully advanced into the left ventricle (LV) under guidance from real-time pressure waveforms. Upon stabilization, continuous pressure and volume signals were recorded through a specialized PV conductance system (MPVS Ultra, emka TECHNOLOGIES, Paris, France) interfaced with a digital converter unit (Model ML-870, ADInstruments, Colorado Springs, CO, USA). Hemodynamic variables were measured across varying preloads induced by transient mechanical compression of the abdominal inferior vena cava. To ascertain preload-independent parameters, transient compressions of the abdominal inferior vena cava were executed concomitantly with PV loop data acquisition.