A case of secondary pseudohypoaldosteronism that presented as poor weight gain.

Key clinical message: Pseudohypoaldosteronism (PHA) carries a good prognosis if treated early and appropriately, but some cases can have life-threatening events. We underscored the need to consider secondary PHA as one of the differential diagnoses of hyponatremia and hyperkalemia in infancy. Abstract: Pseudohypoaldosteronism (PHA) type 1 has two classifications; the primary type, caused by genetic abnormalities that develop during neonatal and infancy periods, and the secondary type, caused by urinary tract malformation and urinary tract infection. Secondary PHA, if treated early and appropriately, has a good prognosis; however, some cases can present life-threatening events. Therefore, early diagnosis is crucial. We present a case of early infancy secondary PHA presented with marked hyponatremia and poor weight gain. The patient's growth and development improved with secondary PHA treatment. Here, were demonstrated the value of prompt action against infection and electrolyte imbalance and the importance of imaging for diagnosis, and underscore the need to consider secondary PHA as a differential diagnoses of hyponatremia and hyperkalemia in infancy. However further studies, including basic research, to elucidate the diseases pathology is warranted.

Ongoing impacts of childhood-onset glomerular diseases during young adulthood.

BACKGROUND: Childhood-onset glomerular disease often requires ongoing treatment and follow-up into adulthood. However, few studies have analyzed the associated impact and distress experienced by patients with this condition during the transition from childhood to adolescence and adulthood. METHODS: At three facilities, we recruited patients who developed idiopathic nephrotic syndrome or IgA nephropathy during childhood and were at least 18 years old at the time of study entry. Among them, a questionnaire-based survey was administered to patients who consented to participate, and the results were analyzed in conjunction with clinical information. RESULTS: Data from a total of 38 patients were analyzed. Of these patients, 15 had idiopathic nephrotic syndrome and 23 had IgA nephropathy. The age of transition from pediatrics to the adult medicine department was correlated with the number of recurrences. Many patients also reported being significantly affected by exercise restrictions and physical decline associated with their diseases and medications. Various impacts, including distress, affected decision-making regarding higher education, with patients engaging in higher education at a significantly higher rate compared with the regional average (66.7% vs. 46.9%, p = 0.028). CONCLUSION: We analyzed the impact of childhood-onset glomerular disease and distress during the transition period from pediatric to adult care. This study highlighted the significant impact of medications and exercise restrictions on patients' decisions regarding higher education. Future prospective studies will be needed to examine patients' distress in more detail and establish management approaches to enhance patient quality of life.

Hydrostatic pressure under hypoxia facilitates fabrication of tissue-engineered vascular grafts derived from human vascular smooth muscle cells in vitro.

Biologically compatible vascular grafts are urgently required. The scaffoldless multi-layered vascular wall is considered to offer theoretical advantages, such as facilitating cells to form cell-cell and cell-matrix junctions and natural extracellular matrix networks. Simple methods are desired for fabricating physiological scaffoldless tissue-engineered vascular grafts. Here, we showed that periodic hydrostatic pressurization under hypoxia (HP/HYP) facilitated the fabrication of multi-layered tunica media entirely from human vascular smooth muscle cells. Compared with normoxic atmospheric pressure, HP/HYP increased expression of N-myc downstream-regulated 1 (NDRG1) and the collagen-cross-linking enzyme lysyl oxidase in human umbilical artery smooth muscle cells. HP/HYP increased N-cadherin-mediated cell-cell adhesion via NDRG1, cell-matrix interaction (i.e., clustering of integrin α5ß1 and fibronectin), and collagen fibrils. We then fabricated vascular grafts using HP/HYP during repeated cell seeding and obtained 10-layered smooth muscle grafts with tensile rupture strength of 0.218-0.396 MPa within 5 weeks. Implanted grafts into the rat aorta were endothelialized after 1 week and patent after 5 months, at which time most implanted cells had been replaced by recipient-derived cells. These results suggest that HP/HYP enables fabrication of scaffoldless human vascular mimetics that have a spatial arrangement of cells and matrices, providing potential clinical applications for cardiovascular diseases. STATEMENT OF SIGNIFICANCE: Tissue-engineered vascular grafts (TEVGs) are theoretically more biocompatible than prosthetic materials in terms of mechanical properties and recipient cell-mediated tissue reconstruction. Although some promising results have been shown, TEVG fabrication processes are complex, and the ideal method is still desired. We focused on the environment in which the vessels develop in utero and found that mechanical loading combined with hypoxia facilitated formation of cell-cell and cell-matrix junctions and natural extracellular matrix networks in vitro, which resulted in the fabrication of multi-layered tunica media entirely from human umbilical artery smooth muscle cells. These scaffoldless TEVGs, produced using a simple process, were implantable and have potential clinical applications for cardiovascular diseases.

Renal arteriovenous fistula discovered ~2 years after renal biopsy: A case report.

Key Clinical Message: Although percutaneous renal biopsy is considered safe, this invasive procedure has complications such as renal arteriovenous fistula (RAVF). Even if complications such as RAVFs are not observed early after renal biopsy, considering the possibility of delayed renal hemorrhage, follow-up with ultrasound after renal biopsy even in asymptomatic cases could be important. Abstract: Although percutaneous renal biopsy is considered safe, this invasive procedure can lead to complications such as renal arteriovenous fistula (RAVF). RAVF occurs when some arteries and veins communicate in the absence of capillaries in the renal hilum or renal parenchyma. It was previously thought to be relatively rare; however, with advances in imaging diagnostics, it is sometimes found asymptomatically. In addition, renal biopsy is the most common cause of acquired RAVF. In this case, RAVF was discovered 2 years after renal biopsy. Late-onset RAVF is scarce. This case highlights that even if complications such as RAVFs are not observed early after renal biopsy, considering the possibility of delayed RAVF, follow-up with ultrasound could be important.

Elective Cesarean Section during Preterm Prevents Pulmonary Hypoplasia Development in Potter Sequence.

Potter syndrome, first reported in 1946 by Edith Potter, refers to fatal cases of bilateral renal aplasia with pulmonary hypoplasia, peculiar facial features, and limb deformities. Presently, patients with oligohydramnios showing similar pathological manifestations due to oligohydramnios caused by conditions other than bilateral renal aplasia have been reported, and are known as the Potter sequence. There are limited studies and unclear guidelines on the safest delivery time and detailed postpartum management for patients with the Potter sequence. We experienced a case of Potter sequence, in which the patient was born by elective cesarean section at gestational age (GA) of 34 weeks. Fetal ultrasound at GA of 26 weeks 4 days showed oligohydramnios, multilocular cystic lesions in the left kidney, and an absent right kidney. Prenatal fetal MRI at GA of 33 weeks and 3 days showed pulmonary hypoplasia, and the ratio of fetal lung volume (FLV) to fetal body weight (FBW) was 0.0135 ml/g. We suspected that the fetal lung could not grow because of persistent oligohydramnios, which leads to a further decline in the ratio of FLV to FBW during pregnancy. We performed a cesarean section at GA of 34 weeks to prevent the exacerbation of the imbalance between lung volume and physique. We struggled to keep her condition stabilized with strict management of her respiratory condition, dialysis, and nutrition. She was discharged from the hospital at 169 days of age. Elective caesarean section in the term of premature birth prevented the progression of pulmonary hypoplasia and made it possible to save her life. Potter sequence is still relatively unknown, and it is necessary for more studies to be conducted in the future.

Store-operated calcium entry via ORAI1 regulates doxorubicin-induced apoptosis and prevents cardiotoxicity in cardiac fibroblasts.

Despite exhibiting cardiotoxicity, doxorubicin (DOX) is widely used for cancer treatments. Cardiac fibroblasts (CFs) are important in the pathogenesis of heart failure. This necessitates the study of the effect of DOX on CFs. The impairment of calcium (Ca2+) homeostasis is a common mechanism of heart failure. Store-operated Ca2+ entry (SOCE) is a receptor-regulated Ca2⁺ entry pathway that maintains calcium balance by sensing reduced calcium stores in the endoplasmic reticulum. ORAI1, a calcium channel protein and the most important component of SOCE, is highly expressed in human cardiac fibroblasts (HCFs). It is upregulated in CFs from failing ventricles. However, whether ORAI1 in HCFs is increased and/or plays a role in DOX-induced cardiotoxicity remains unknown. In this study, we aimed to elucidate the relationship between ORAI1/SOCE and DOX-induced heart failure. Induction of apoptosis by DOX was characterized in HCFs. Apoptosis and cell cycle analyses were performed by fluorescence-activated cell sorting (FACS). Reactive oxygen species (ROS) production was measured using fluorescence. YM-58483 was used as an ORAI1/SOCE inhibitor. ORAI1-knockdown cells were established by RNA interference. In vivo experiments were performed by intraperitoneally injecting YM-58483 and DOX into mice. We first demonstrated that DOX significantly increased the protein expression level of p53 in HCFs by western blotting. FACS analysis revealed that DOX increased early apoptosis and induced cell cycle arrest in the G2 phase in fibroblasts. DOX also increased ROS production. DOX significantly increased the expression level of ORAI1 in CFs. Both YM-58483 and ORAI1 gene knockdown attenuated DOX-induced apoptosis. Similarly, YM-58483 attenuated cell cycle arrest in the G2 phase, and ORAI1 knockdown attenuated DOX-induced ROS production in HCFs. In the animal experiment, YM-58483 attenuated DOX-induced apoptosis. In HCFs, ORAI1/SOCE regulates p53 expression and plays an important role in DOX-induced cardiotoxicity. ORAI1 may serve as a new target for preventing DOX-induced heart failure.

Cyclosporine therapy could be considered for membranoproliferative glomerulonephritis with immunoglobulin A deposits: a case report.

BACKGROUND: Membranoproliferative glomerulonephritis (MPGN), a rare glomerulonephritis that causes nephrotic syndrome in children, is often difficult to treat. Typical immunofluorescence findings include strong C3 staining in a granular pattern along the glomerular capillary wall and negative IgA staining. IgA-dominant MPGN without hypocomplementemia has been reported. Herein, we report a rare case of MPGN with hypocomplementemia and predominant IgA subclass 2 deposits. CASE PRESENTATION: An 11-year-old girl showed proteinuria on a school urinalysis screening and presented with upper eyelid edema. The urinalysis showed elevated urinary protein levels and hematuria. Laboratory examinations revealed the following: serum albumin, 1.3 g/dL; serum creatinine, 0.54 mg/dL; and C3c, 67 mg/dL (normal range: 73-138 mg/dL). The physical and laboratory findings did not suggest autoimmune diseases. A renal biopsy was then performed. Specimen examination under a light microscope showed mesangial cell proliferation, increased mesangial matrix with lobulation, and some double contours of the glomerular basement membrane in almost all glomeruli, which are characteristic findings of MPGN. Immunofluorescent studies showed IgA deposits not only in the mesangial regions but also along the capillary walls, which were more strongly stained than C3. IgA subclass staining showed a stronger immunoreactivity for IgA2 than IgA1. Electron microscopic studies showed electron-dense deposits in the subendothelial, subepithelial, and paramesangial regions. Based on these findings, the patient was diagnosed with IgA-dominant MPGN. Accordingly, she was treated with three courses of methylprednisolone pulse therapy (MPT), followed by prednisolone, mizoribine, and lisinopril. Although hypocomplementemia improved after three courses of MPT, nephrotic-range proteinuria and hypoalbuminemia remained; therefore, two courses of MPT were additionally administered, and the immunosuppressant was changed from mizoribine to cyclosporine (CsA). Finally, the urinary protein level decreased, and a subsequent renal biopsy, two years later, showed improvement in the lesions. CONCLUSIONS: We report an atypical case of MPGN with IgA2 dominant deposits along the glomerular capillary wall and in the mesangial region. The case was refractory to standard therapy but sensitive to CsA, which resulted in remission. Our findings suggest that CsA may be useful as an immunosuppressant to treat refractory MPGN.

Predictors of hematoma as a complication in pediatric kidney biopsies.

BACKGROUND: Kidney biopsies are crucial in the diagnosis of kidney diseases but they carry the risk of various complications, most commonly hematoma. Here we tried to identify the predictors of hematomas as a complication of kidney biopsies and we constructed an algorithm to stratify the risk. METHODS: The present report retrospectively reviewed 118 pediatric percutaneous kidney biopsies of native kidneys in 102 children (59 females) with the median age of 9 years (range: 1-19 years) at Kumamoto University Hospital between August 2008 and October 2019. We defined hematoma size using the hematoma index: the short axis of the hematoma/major axis of the kidney on ultrasonography. The inclusion criteria for a hematoma as a complication of a kidney biopsy were hematoma index ≥0.1 and the presence of concomitant, post-kidney biopsy fever or flank pain. RESULTS: Eight patients presented with a hematoma as a complication. All had hematoma index ≥0.1 and age ≥6 years. On univariate logistic analysis, these patients had a larger hemoglobin (Hgb) decrease on post-biopsy day 1, which was unrelated to a Hgb decrease 2 h after the biopsy, than the patients with no hematoma. All eight patients with a hematoma presented with a fever or flank pain on post-biopsy days 5 to 7, underscoring the need to observe patients with decreased Hgb carefully for about 1 week after a biopsy. CONCLUSION: Predictors of hematoma as a complication in children after a kidney biopsy were hematoma index ≥0.1, age >6 years, and Hgb decrease ≥15% on post-biopsy day 1.

A Case of Nephrotic Syndrome that Resolved with Influenza B Infection.

It has been postulated that measles virus infection is associated with remission of idiopathic nephrotic syndrome (INS) in childhood. There are few reports on the correlation of INS remission with other infections. Previously, there have been two case reports suggesting an association between influenza B virus infection and the remission of INS. The patient was an 18-year-old Japanese woman. The onset of steroid-sensitive NS was at 9 years of age, and pathological diagnosis was minimal change nephrotic syndrome (MCNS). Until 10 months prior to visiting our hospital, the patient's NS was in remission. The patient experienced fever, cough, and malaise and she was diagnosed with type B influenza by a local physician 4 days before visiting our hospital. The patient had vomiting and diarrhea 1 day prior to visiting our hospital. Her weight was 54.7 kg (+5.0 kg) and she had pitting edema of both lower legs. Her serum albumin level was 0.9 g/dL, proteinuria level was 8.73 g/gCr, and urine sediments showed 1-4 red blood cells per high-power field. She was diagnosed with relapse of NS. The level of proteinuria decreased to 0.03 g/gCr with rest alone on day 4 of admission, and a complete remission from NS was observed at approximately 2 weeks after the onset of influenza B infection. We report a rare case wherein spontaneous remission of NS occurred within a short period of 2 weeks after influenza B infection. It is clear that some immunity is involved in the pathogenesis of INS, but there are some cases in which infection improves NS and others in which it recurs.

Multilayered Human Skeletal Muscle Myoblast Sheets Promote the Healing Process After Colonic Anastomosis in Rats.

Colorectal anastomotic leakage is one of the most feared and fatal complications of colorectal surgery. To date, no external coating material that can prevent anastomotic leakage has been developed. As myoblasts possess anti-inflammatory capacity and improve wound healing, we developed a multilayered human skeletal muscle myoblast (HSMM) sheet by periodic exposure to supraphysiological hydrostatic pressure during repeated cell seeding. We assessed whether the application of an HSMM sheet can promote the healing process after colonic anastomosis. Partial colectomy and insufficient suturing were employed to create a high-risk colo-colonic anastomosis model in 60 nude rats. Rats were divided into a control group (n = 30) and an HSMM sheet group (n = 30). Macroscopic findings, anastomotic bursting pressure, and histology at the colonic anastomotic site were evaluated on postoperative day (POD) 3, 5, 7, 14, and 28. The application of an HSMM sheet significantly suppressed abscess formation at the anastomotic site compared to the control group on POD3 and 5. The anastomotic bursting pressure in the HSMM sheet group was higher than that in the control group on POD3 and 5. Inflammatory cell infiltration in the HSMM sheet group was significantly suppressed compared to that in the control group throughout the time course. Collagen deposition in the HSMM sheet group on POD3 was significantly abundant compared to that in the control group. Regeneration of the mucosa at the colonic anastomotic site was promoted in the HSMM sheet group compared to that in the control group on POD14 and 28. Immunohistochemical analysis demonstrated that surviving cells in the HSMM sheet gradually decreased with postoperative time and none were detected on POD14. These results suggest that the application of a multilayered HSMM sheet may prevent postoperative colonic anastomotic leakage.

Impact of the 2016 Kumamoto earthquake on patients with nephrogenic diabetes insipidus and preparations for the future.

Patients with nephrogenic diabetes insipidus should establish a support network system by contacting the government to ensure that water can be preferentially obtained in the event of a disaster and create and carry a medical alert card.

Translationally controlled tumor protein (TCTP) plays a pivotal role in cardiomyocyte survival through a Bnip3-dependent mechanism.

Prevention of cardiomyocyte death is an important therapeutic strategy for heart failure. In this study, we focused on translationally controlled tumor protein (TCTP), a highly conserved protein that is expressed ubiquitously in mammalian tissues, including heart. TCTP plays pivotal roles in survival of certain cell types, but its function in cardiomyocytes has not been examined. We aimed to clarify the role of TCTP in cardiomyocyte survival and the underlying mechanism. Here, we demonstrated that downregulation of TCTP with siRNA induced cell death of cardiomyocytes with apoptotic and autophagic features, accompanied with mitochondrial permeability transition pore (mPTP) opening. TCTP loss did not induce cell death of cardiac fibroblasts. Bcl-2/adenovirus E1B 19-kDa interacting protein 3 (Bnip3) was found to mediate the TCTP-loss-induced cardiomyocyte death. In exploring the clinical significance of the TCTP expression in the heart, we found that DOX treatment markedly downregulated the protein expression of TCTP in cultured cardiomyocytes and in mouse heart tissue. Exogenous rescue of TCTP expression attenuated DOX-induced cardiomyocyte death. In mice, cardiomyocyte-specific overexpression of TCTP resulted in decreased susceptibility to DOX-induced cardiac dysfunction, accompanied with attenuated induction of Bnip3. Dihydroartemisinin, a pharmacological TCTP inhibitor, induced development of heart failure and cardiomyocyte death in control mice, but not in mice with cardiomyocyte-specific TCTP overexpression. Our findings revealed TCTP has a pivotal role in cardiomyocyte survival, at least in part through a Bnip3-dependent mechanism. TCTP could be considered as a candidate therapeutic target to prevent DOX-induced heart failure.

Correction to: Epac activation inhibits IL-6-induced cardiac myocyte dysfunction.

The article Epac activation inhibits IL-6-induced cardiac myocyte dysfunction.

Usefulness of Exchanged Protein Directly Activated by cAMP (Epac)1-Inhibiting Therapy for Prevention of Atrial and Ventricular Arrhythmias in Mice.

BACKGROUND: It has been suggested that protein directly activated by cAMP (Epac), one of the downstream signaling molecules of ß-adrenergic receptor (ß-AR), may be an effective target for the treatment of arrhythmia. However, there have been no reports on the anti-arrhythmic effects or cardiac side-effects of Epac1 inhibitors in vivo. Methods and Results: In this study, the roles of Epac1 in the development of atrial and ventricular arrhythmias are examined. In addition, we examined the usefulness of CE3F4, an Epac1-selective inhibitor, in the treatment of the arrhythmias in mice. In Epac1 knockout (Epac1-KO) mice, the duration of atrial fibrillation (AF) was shorter than in wild-type mice. In calsequestrin2 knockout mice, Epac1 deficiency resulted in a reduction of ventricular arrhythmia. In both atrial and ventricular myocytes, sarcoplasmic reticulum (SR) Ca2+ leak, a major trigger of arrhythmias, and spontaneous SR Ca2+ release (SCR) were attenuated in Epac1-KO mice. Consistently, CE3F4 treatment significantly prevented AF and ventricular arrhythmia in mice. In addition, the SR Ca2+ leak and SCR were significantly inhibited by CE3F4 treatment in both atrial and ventricular myocytes. Importantly, cardiac function was not significantly affected by a dosage of CE3F4 sufficient to exert anti-arrhythmic effects. CONCLUSIONS: These findings indicated that Epac1 is involved in the development of atrial and ventricular arrhythmias. CE3F4, an Epac1-selective inhibitor, prevented atrial and ventricular arrhythmias in mice.

Vidarabine, an anti-herpesvirus agent, prevents catecholamine-induced arrhythmias without adverse effect on heart function in mice.

Sympathetic activation causes clinically important arrhythmias including atrial fibrillation (AF) and ventricular tachyarrhythmia. Although the usefulness of ß-adrenergic receptor blockade therapy is widely accepted, its multiple critical side effects often prevent its initiation or continuation. The aim of this study is to determine the advantages of vidarabine, an adenylyl cyclase (AC)-targeted anti-sympathetic agent, as an alternative treatment for arrhythmia. We found that vidarabine, which we identified as a cardiac AC inhibitor, consistently shortens AF duration and reduces the incidence of sympathetic activation-induced ventricular arrhythmias. In atrial and ventricular myocytes, vidarabine inhibits adrenergic receptor stimulation-induced RyR2 phosphorylation, sarcoplasmic reticulum (SR) Ca2+ leakage, and spontaneous Ca2+ release from SR, the last of which has been considered as a potential arrhythmogenic trigger. Moreover, vidarabine also inhibits sympathetic activation-induced reactive oxygen species (ROS) production in cardiac myocytes. The pivotal role of vidarabine's inhibitory effect on ROS production with regard to its anti-arrhythmic property has also been implied in animal studies. In addition, as expected, vidarabine exerts an inhibitory effect on AC function, which is more potent in the heart than elsewhere. Indexes of cardiac function including ejection fraction and heart rate were not affected by a dosage of vidarabine sufficient to exert an anti-arrhythmic effect. These findings suggest that vidarabine inhibits catecholamine-induced AF or ventricular arrhythmia without deteriorating cardiac function in mice.

Epac activation inhibits IL-6-induced cardiac myocyte dysfunction.

Pro-inflammatory cytokines are released in septic shock and impair cardiac function via the Jak-STAT pathway. It is well known that sympathetic and thus catecholamine signaling is activated thereafter to compensate for cardiac dysfunction. The mechanism of such compensation by catecholamine signaling has been traditionally understood to be cyclic AMP-dependent protein kinase (PKA)-mediated enforcement of cardiac contractility. We hypothesized that the exchange protein activated by cAMP (Epac), a newly identified target of cAMP signaling that functions independently of PKA, also plays a key role in this mechanism. In cultured cardiac myocytes, activation of Epac attenuated the inhibitory effect of interleukin-6 on the increase of intracellular Ca2+ concentration and contractility in response to isoproterenol, most likely through inhibition of the Jak-STAT pathway via SOCS3, with subsequent changes in inducible nitric oxide synthase expression. These findings suggest a new role of catecholamine signaling in compensating for cardiac dysfunction in heart failure. Epac and its downstream pathway may be a novel target for treating cardiac dysfunction in endotoxemia.

Cardiac overexpression of Epac1 in transgenic mice rescues lipopolysaccharide-induced cardiac dysfunction and inhibits Jak-STAT pathway.

Pro-inflammatory cytokines are released in septic shock and impair cardiac function via the Jak-STAT pathway. It is well known that sympathetic stimulation leads to coupling of the ß-adrenergic receptor/Gs/adenylyl cyclase, a membrane-bound enzyme that catalyzes the conversion of ATP to cAMP, thereby stimulating protein kinase A (PKA) and ultimately compensating for cardiac dysfunction. The mechanism of such compensation by catecholamine has been traditionally understood as PKA-mediated enforcement of cardiac contractility. We hypothesized that exchange protein activated by cyclic AMP (Epac), a new target of cAMP signaling that functions independently of protein kinase A, also plays a key role in protection against acute stresses or changes in hemodynamic overload. Lipopolysaccharide injection induced cytokine release and severe cardiac dysfunction in mouse. In mouse overexpressing Epac1 in the heart, however, the magnitude of such dysfunction was significantly smaller. Epac1 overexpression inhibited the Jak-STAT pathway, as indicated by decreased phosphorylation of STAT3 and increased SOCS3 expression, with subsequent inhibition of iNOS expression. In cultured cardiomyocytes treated with isoproterenol or forskolin, the increase of SOCS3 expression was blunted when Epac1 or PKCα was silenced with siRNA. Activation of the cAMP/Epac/PKCα pathway protected the heart against cytokine-induced cardiac dysfunction, suggesting a new role of catecholamine signaling in compensating for cardiac dysfunction in heart failure. Epac1 and its downstream pathways may be novel targets for treating cardiac dysfunction in endotoxemia.

Vidarabine, an Anti-Herpes Virus Agent, Protects Against the Development of Heart Failure With Relatively Mild Side-Effects on Cardiac Function in a Canine Model of Pacing-Induced Dilated Cardiomyopathy.

BACKGROUND: In heart failure patients, chronic hyperactivation of sympathetic signaling is known to exacerbate cardiac dysfunction. In this study, the cardioprotective effect of vidarabine, an anti-herpes virus agent, which we identified as a cardiac adenylyl cyclase inhibitor, in dogs with pacing-induced dilated cardiomyopathy (DCM) was evaluated. In addition, the adverse effects of vidarabine on basal cardiac function was compared to those of the ß-blocker, carvedilol.Methods and Results:Vidarabine and carvedilol attenuated the development of pacing-induced systolic dysfunction significantly and with equal effectiveness. Both agents also inhibited the development of cardiac apoptosis and fibrosis and reduced the Na+-Ca2+exchanger-1 protein level in the heart. Importantly, carvedilol significantly enlarged the left ventricle and atrium; vidarabine, in contrast, did not. Vidarabine-treated dogs maintained cardiac response to ß-AR stimulation better than carvedilol-treated dogs did. CONCLUSIONS: Vidarabine may protect against pacing-induced DCM with less suppression of basal cardiac function than carvedilol in a dog model. (Circ J 2016; 80: 2496-2505).

Disruption of Epac1 protects the heart from adenylyl cyclase type 5-mediated cardiac dysfunction.

Type 5 adenylyl cyclase (AC5) plays an important role in the development of chronic catecholamine stress-induced heart failure and arrhythmia in mice. Epac (exchange protein activated by cAMP), which is directly activated by cAMP independent of protein kinase A, has been recently identified as a novel mediator of cAMP signaling in the heart. However, the role of Epac in AC5-mediated cardiac dysfunction and arrhythmias remains poorly understood. We therefore generated AC5 transgenic mice (AC5TG) with selective disruption of the Epac1 gene (AC5TG-Epac1KO), and compared their phenotypes with those of AC5TG after chronic isoproterenol (ISO) infusion. Decreased cardiac function as well as increased susceptibility to pacing-induced atrial fibrillation (AF) in response to ISO were significantly attenuated in AC5TG-Epac1KO mice, compared to AC5TG mice. Increased cardiac apoptosis and cardiac fibrosis were also concomitantly attenuated in AC5TG-Epac1KO mice compared to AC5TG mice. These findings indicate that Epac1 plays an important role in AC5-mediated cardiac dysfunction and AF susceptibility.