Itions of RV pressure overload (RVPO) within an intact pericardium, reducedRV output will impact left ventricular (LV) function by decreasing LV preload, increasing coronary sinus pressure, and mechanically impinging on the LV throughout the cardiac cycle [12?3]. While biventricular interactions have been the subject of intensive study in left heart failure, few studies in RVPO have focused on RV remodeling [14?7]. The impact of RVPO on biventricular function remains poorly characterized. As the thin-walled RV dilates in the setting of pressure overload, increased RV wall 10457188 stress activates signaling cascades that promote cardiac hypertrophy and fibrosis including the transforming growth factor beta-1 (TGFb1) and calcineurin pathways. TGFb1 is a powerful pro-fibrogenic cytokine that signals through a heteromeric receptor complex comprised of a Type II ligandbinding receptor, Type I activin like kinase (ALK) signaling receptors, and the Type III accessory co-receptor, Endoglin. Upon TGFb1 activation, this receptor complex phosphorylates downstream effector proteins known as Smads (canonical pathway) or mitogen activated protein kinases, like extracellular regulated kinase (ERK; non-canonical pathway) [18?0]. Specifically, TGFb1-induced phosphorylation of Smad-2/3 and ERK proBiventricular Remodelingmotes Type I collagen synthesis and fibrosis. Given its central role in stimulating fibrosis, TGFb1 has been non-selectively targeted in models of left heart failure, using multiple approaches; none of which have produced clearly beneficial therapeutic effects [21,22]. TGFb1 signaling in RV remodeling has remained largely ignored. Models of left heart failure have also confirmed the central role of the calcium-dependent serine/threonine phosphatase, calcineurin, as a mediator of maladaptive hypertrophy secondary to pressure overload. Calcineurin dephosphorylates nuclear factor of activated T cells (NFAT), a family of cytoplasmic transcription factors that promote gene expression that regulates cardiac hypertrophy [23,24]. Recent studies have also implicated calcineurin as a key regulator of cardiac fibrosis [25]. Few studies have examined the impact of these signaling pathways in RV and LV remodeling in the setting of RVPO [26]. Given the increasing use of murine models of left heart failure and PH, the objective of this study was to demonstrate a novel percutaneous approach to study biventricular hemodynamics in clinically relevant murine models of primary and secondary RVPO and further explore biventricular expression of two key proteins that regulate cardiac remodeling: calcineurin and TGFb1.were placed at the proximal ends with 7-0 nylon. Millar PVR1035 and PVR-1045 (Millar Instruments, Inc.; Houston, Texas) mouse conductance catheters and S were transfected with pshRNA-UBE2D3 and negative control. Samples were independent consoles were used for right and left ventricular recordings respectively. Prior to insertion, conductance catheter calibration was performed using the cuvette method with Title Loaded From File freshly heparinized warm blood as previously described [15]. Both catheters were then zeroed in warm saline. A transverse venotomy was performed using iris scissors at the proximal end of the external jugular vein. The PVR-1035 catheter was advanced through the SVC and right atrium into the right ventricle. For LV cannulation, a micro vascular clip was first placed proximal to the nylon overhand loop, then a transverse arteriotomy was performed with iris scissors and the PVR-1045 catheter was advanced to the clip. The proximal.Itions of RV pressure overload (RVPO) within an intact pericardium, reducedRV output will impact left ventricular (LV) function by decreasing LV preload, increasing coronary sinus pressure, and mechanically impinging on the LV throughout the cardiac cycle [12?3]. While biventricular interactions have been the subject of intensive study in left heart failure, few studies in RVPO have focused on RV remodeling [14?7]. The impact of RVPO on biventricular function remains poorly characterized. As the thin-walled RV dilates in the setting of pressure overload, increased RV wall 10457188 stress activates signaling cascades that promote cardiac hypertrophy and fibrosis including the transforming growth factor beta-1 (TGFb1) and calcineurin pathways. TGFb1 is a powerful pro-fibrogenic cytokine that signals through a heteromeric receptor complex comprised of a Type II ligandbinding receptor, Type I activin like kinase (ALK) signaling receptors, and the Type III accessory co-receptor, Endoglin. Upon TGFb1 activation, this receptor complex phosphorylates downstream effector proteins known as Smads (canonical pathway) or mitogen activated protein kinases, like extracellular regulated kinase (ERK; non-canonical pathway) [18?0]. Specifically, TGFb1-induced phosphorylation of Smad-2/3 and ERK proBiventricular Remodelingmotes Type I collagen synthesis and fibrosis. Given its central role in stimulating fibrosis, TGFb1 has been non-selectively targeted in models of left heart failure, using multiple approaches; none of which have produced clearly beneficial therapeutic effects [21,22]. TGFb1 signaling in RV remodeling has remained largely ignored. Models of left heart failure have also confirmed the central role of the calcium-dependent serine/threonine phosphatase, calcineurin, as a mediator of maladaptive hypertrophy secondary to pressure overload. Calcineurin dephosphorylates nuclear factor of activated T cells (NFAT), a family of cytoplasmic transcription factors that promote gene expression that regulates cardiac hypertrophy [23,24]. Recent studies have also implicated calcineurin as a key regulator of cardiac fibrosis [25]. Few studies have examined the impact of these signaling pathways in RV and LV remodeling in the setting of RVPO [26]. Given the increasing use of murine models of left heart failure and PH, the objective of this study was to demonstrate a novel percutaneous approach to study biventricular hemodynamics in clinically relevant murine models of primary and secondary RVPO and further explore biventricular expression of two key proteins that regulate cardiac remodeling: calcineurin and TGFb1.were placed at the proximal ends with 7-0 nylon. Millar PVR1035 and PVR-1045 (Millar Instruments, Inc.; Houston, Texas) mouse conductance catheters and independent consoles were used for right and left ventricular recordings respectively. Prior to insertion, conductance catheter calibration was performed using the cuvette method with freshly heparinized warm blood as previously described [15]. Both catheters were then zeroed in warm saline. A transverse venotomy was performed using iris scissors at the proximal end of the external jugular vein. The PVR-1035 catheter was advanced through the SVC and right atrium into the right ventricle. For LV cannulation, a micro vascular clip was first placed proximal to the nylon overhand loop, then a transverse arteriotomy was performed with iris scissors and the PVR-1045 catheter was advanced to the clip. The proximal.
