Cardiomyocyte-Specific Deletion of Orai1 Reveals Its Protective Role in Angiotensin-II-Induced Pathological Cardiac Remodeling

Pathological cardiac remodeling correlates with chronic neurohumoral stimulation and abnormal Ca2+ signaling in cardiomyocytes. Store-operated calcium entry (SOCE) has been described in adult and neonatal murine cardiomyocytes, and Orai1 proteins act as crucial ion-conducting constituents of this calcium entry pathway that can be engaged not only by passive Ca2+ store depletion but also by neurohumoral stimuli such as angiotensin-II. In this study, we, therefore, analyzed the consequences of Orai1 deletion for cardiomyocyte hypertrophy in neonatal and adult cardiomyocytes as well as for other features of pathological cardiac remodeling including cardiac contractile functionin vivo. Cellular hypertrophyinduced by angiotensin-IIin embryonic cardiomyocytes from Orai1-deficient mice was blunted in comparison to cells from litter-matched control mice. Due to lethality of mice with ubiquitous Orai1 deficiency and to selectively analyze the role of Orai1 in adult cardiomyocytes, we generated a cardiomyocyte-specific and temporally inducible Orai1 knockout mouse line (Orai1CM–KO). Analysis of cardiac contractility by pressure-volume loops under basal conditions and of cardiac histology did not reveal differences between Orai1CM–KO mice and controls. Moreover, deletion of Orai1in cardiomyocytesin adultmice did not protect them from angiotensin-II-induced cardiac remodeling, but cardiomyocyte cross-sectional area and cardiac fibrosis were enhanced. These alterations in the absence of Orai1 go along with blunted angiotensin-II-induced upregulation of the expression of Myoz2 and a lack of rise in angiotensin-II-induced STIM1 and Orai3 expression. In contrast to embryonic cardiomyocytes, where Orai1 contributes to the development of cellular hypertrophy, the results obtained from deletion of Orai1 in the adult myocardium reveal a protective function of Orai1 against the development of angiotensin-II-induced cardiac remodeling, possibly involving signaling via Orai3/STIM1-calcineurin-NFAT related pathways

Assessment of PEEP-Ventilation and the Time Point of Parallel-Conductance Determination for Pressure-Volume Analysis Under β-Adrenergic Stimulation in Mice

Aim: Cardiac pressure-volume (PV loop) analysis under β-adrenergic stimulation is a powerful method to simultaneously determine intrinsic cardiac function and β-adrenergic reserve in mouse models. Despite its wide use, several key approaches of this method, which can affect murine cardiac function tremendously, have not been experimentally investigated until now. In this study, we investigate the impact of three lines of action during the complex procedure of PV loop analysis: (i) the ventilation with positive end-expiratory pressure, (ii) the time point of injecting hypertonic saline to estimate parallel-conductance, and (iii) the implications of end-systolic pressure-spikes that may arise under β-adrenergic stimulation.Methods and Results: We performed pressure-volume analysis during β-adrenergic stimulation in an open-chest protocol under Isoflurane/Buprenorphine anesthesia. Our analysis showed that (i) ventilation with 2 cmH2O positive end-expiratory pressure prevented exacerbation of peak inspiratory pressures subsequently protecting mice from macroscopic pulmonary bleedings. (ii) Estimations of parallel-conductance by injecting hypertonic saline prior to pressure-volume recordings induced dilated chamber dimensions as depicted by elevation of end-systolic volume (+113%), end-diastolic volume (+40%), and end-diastolic pressure (+46%). Further, using this experimental approach, the preload-independent contractility (PRSW) was significantly impaired under basal conditions (−17%) and under catecholaminergic stimulation (−14% at 8.25 ng/min Isoprenaline), the β-adrenergic reserve was alleviated, and the incidence of ectopic beats was increased >5-fold. (iii) End-systolic pressure-spikes were observed in 26% of pressure-volume recordings under stimulation with 2.475 and 8.25 ng/min Isoprenaline, which affected the analysis of maximum pressure (+11.5%), end-diastolic volume (−8%), stroke volume (−10%), and cardiac output (−11%).Conclusions: Our results (i) demonstrate the advantages of positive end-expiratory pressure ventilation in open-chest instrumented mice, (ii) underline the perils of injecting hypertonic saline prior to pressure-volume recordings to calibrate for parallel-conductance and (iii) emphasize the necessity to be aware of the consequences of end-systolic pressure-spikes during β-adrenergic stimulation

Idiopathic elevated episcleral venous pressure in a teenager.

PURPOSE: To report a case of unilateral idiopathic elevated episcleral venous pressure (IEEVP) in a 15-year-old patient. We reviewed and summarized published case reports of IEEVP to determine how to manage this challenging and rare condition. OBSERVATIONS: A 15-year-old Caucasian male presented with elevated intraocular pressures (IOP), blood in Schlemm canal in the left eye, and asymmetric cupping with corresponding glaucomatous findings on testing. We diagnosed the patient with IEEVP and describe successful surgical intervention with deep sclerectomy and viscocanalostomy. CONCLUSIONS AND IMPORTANCE: IEEVP is a diagnosis of exclusion and based on clinical findings of dilated episcleral veins, blood in Schlemm canal and glaucomatous changes. If glaucomatous progression occurs with medication, filtration surgery is usually required, and most patients have good results in the literature. Care should be taken to prevent post-operative hypotony and serous choroidal detachment

Idiopathic elevated episcleral venous pressure in a teenager

To report a case of unilateral idiopathic elevated episcleral venous pressure (IEEVP) in a 15-year-old patient. We reviewed and summarized published case reports of IEEVP to determine how to manage this challenging and rare condition. A 15-year-old Caucasian male presented with elevated intraocular pressures (IOP), blood in Schlemm canal in the left eye, and asymmetric cupping with corresponding glaucomatous findings on testing. We diagnosed the patient with IEEVP and describe successful surgical intervention with deep sclerectomy and viscocanalostomy. IEEVP is a diagnosis of exclusion and based on clinical findings of dilated episcleral veins, blood in Schlemm canal and glaucomatous changes. If glaucomatous progression occurs with medication, filtration surgery is usually required, and most patients have good results in the literature. Care should be taken to prevent post-operative hypotony and serous choroidal detachment