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Cardiac catheterization.

Hemodynamic evaluation of both infected and uninfected tg
mice was performed while animals under anesthesia with Ketamine (100 mg/kg) and
Xylazine (10 mg/kg), mice were intubated and placed supine position on a ventilator
followed by the right carotid artery and external jugular vein exposure. A 1.4F
conductance catheter (Millar Instruments, Inc.) was passed retrogradely through the right
carotid artery into the left ventricle (LV). To minimize the effect of autonomic nerve on
hemodynamics parameters, vagus nerves were cut before baseline pressure-volume loop
(PV loop) recording. To examine LV systolic function and chamber stiffness, PV loops
were recorded for the sequence of beats during the transient decrease in preload through
the occlusion of the inferior vena cava running beside the right kidney. Load-independent
LV contractility, Emax, was calculated as the slope of the linear end-systolic pressurevolume
relation (ESPVR). LV chamber stiffness was assessed with the slope of the linear
regression analysis of the end-diastolic pressure-volume relation (EDPVR) The effective
arterial elastance (Ea) was determined as the ratio of end-systolic pressure to stroke
volume (S4). The ratio of Ea to ventricular elastance (Ea/Emax) represents
ventriculoarterial coupling that is known to reflect the mechanoenergetic performance of
the heart. Measured time-varying conductance (relative volume unit) was converted to
time-varying volume (μl) based on actual LV volume calculated from biplane left
vetriculography with Simpson’s rule method as described previously (S5). The time
constant of left ventricular pressure decay, Tau, was evaluated according to the methods
of Weiss et al. (S6). All analysis was performed using IOX1.8.5 software (EMKA
Technologies).