Spr 869

Arterial blood pressure was measured with a conductance catheter in anaesthetized animals as previously described [15 (link),42 (link),85 (link)]. Briefly, A pressure conductance catheter (SPR-869; Millar, USA) was placed into the right carotid artery. After a 30 min equilibration period, baseline arterial blood pressure was recorded. Baseline hemodynamic parameters were: systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP) and heart rate (HR). No significant differences in PaO₂ has been previously showed between Sham and HF rats [15 (link)].

LV function was evaluated using a pressure–volume (PV) conductance catheter (SPR-869, Millar) [33 , 39 (link)]. Under anesthesia (α-chloralose and urethane, 800 mg Kg⁻¹ and 40 mg Kg⁻¹, respectively) a conductance catheter was introduced into right carotid artery and advance toward LV chamber. A laparotomy was performed to visualized arteriovenous fistula and then perform a cava vein occlusion. PV-loops were recorded for 1 h and fifteen to twenty PV loops were used to calculate hemodynamic parameters: cardiac output (CO), ejection fraction (EF), end diastolic pressure (EDP), end systolic pressure (ESP), Parameters dependent of load were: dP/dt_max, dP/dt_min. Load-independent parameters: end-systolic pressure volume relationship (ESPVR) and end-diastolic pressure volume relationship (EDPVR) were also calculated. Data was processed using the PV-loop module of LabChart v7.3.8 software (ADInstruments).

Rats were anesthetized with ~3% isoflurane delivered by a nose cone. The right carotid was dissected from the surrounding structures with care taken to avoid damaging the vagus nerve. The rostral portion of the carotid was ligated with silk suture, and a SPR-869 (Millar) catheter was introduced into the carotid while proximal flow was occluded with a bulldog clamp. The clamp was then removed, the catheter rapidly advanced and a suture was placed to prevent blood loss. The catheter was then advanced into the left ventricle. Pressure signals were recorded through an MPVS-400 analog to digital converter interface (Millar) and analyzed using Labchart version 8 software (ADInstruments).

Approximately 6 weeks post-injection, all implanted rats were anesthetized using isoflurane (2% in oxygen), intubated and ventilated. Arterial pressure and heart rate were monitored throughout via the implanted telemeter. Incisions were made in the chest and diaphragm to allow insertion of a pressure-volume catheter (SPR-838, Millar Inc) into the left ventricle, and a second pressure-volume catheter (model SPR-869, Millar Inc) into the right ventricle. Simultaneous measurement was not possible due to interference between the two catheters. Hence, the order of ventricular recordings was randomized. Data were acquired for computer analysis using the LabChart 7 software system (Powerlab, ADInstruments).

Rats were anaesthetized with a mixture of 800 mg/kg urethane (SIGMA, USA) and 40 mg/kg α-chloralose (SIGMA, USA). A transducer catheter (SPR-869, MILLAR INSTRUMENTS) was introduced into the left ventricle through the right carotid. Cardiac left ventricle pressure-volume (PV) loops were recorded at steady state. Measurements were calibrated by injecting a hypertonic saline bolus (30% wt/vol NaCl) to determine conductance, and relative volume units were converted absolute using the cuvette calibration method. The LV end-of-systole volume (LVESV), LV end-diastolic volume (LVEDV), LV end-systole pressure (LVESP), LV end-diastolic pressure (LVEDP), ejection volume (SV), cardiac output (CO) and ejection fraction (EF) were obtained from 10–15 representative loops. Volume at pressure 0 and End-Systolic Pressure-Volume Relationship (ESPVR) were used as indicators of diastolic and systolic function, respectively. These analyses were calculated by a mathematical algorithm from a single beat obtained from pressure-volume curves according to Klotz et al.^{21 (link)} for V-0 and Takeushi et al.^{22 (link)} for ESPVR. All recordings were sampled to 1 kHz and were analyzed using LABCHART7 Pro v7.2 software (ADINSTRUMENTS)^{18 (link),19 (link),21 (link),22 (link),49 (link)}.