Rationale: Point‐of‐care ultrasound (POCUS) is used to evaluate pulmonary edema in adults with acute respiratory distress syndrome (ARDS). Its use has not been validated in neonatal models.Objectives: We compared an in vivo lung ultrasound score against clinical and histological markers of acute lung injury, in a neonatal animal model, hypothesizing that POCUS would sensitively diagnose early acute lung injury in neonates and discern its severity.Methods: Fifteen anesthetized, ventilated 3‐day‐old neonatal piglets were divided into controls, moderate lung injury, or severe lung injury by graded treatment with oleic acid. Degree of lung injury was quantified at baseline, immediately after oleic acid administration, and 1 hour after the evolution of acute lung injury, by blood gases, ventilation parameters and calculated oxygenation deficit; hemodynamic indices by echocardiography, and lung ultrasound obtained in an 8‐region grid of anterior and posterior zones, semi‐quantitatively analyzed by a blinded observer. Lungs were inflation‐fixed postmortem at last mean airway pressure, for histological assessment.Results: Acute lung injury manifested in oleic acid‐treated groups as dose‐dependent capillary leak causing intravascular depletion and cardiac failure, hypoxemia with increasing intrapulmonary shunt fraction, decreased lung compliance, and resistance. Ultrasound scores of anterior regions distinguished moderate from severe injury; scores in posterior regions reached maximum values immediately after lung injury. POCUS score correlated with calculated intrapulmonary shunt fraction (R² = .65) and with histological injury score (R² = .61),P < .01.Conclusion: We conclude that POCUS may be valuable in neonates for early quantification of acute lung injury or ARDS; and that nondependent ultrasound regions clearly distinguish severity of pulmonary edema.

Adenylyl cyclases (ACs) are crucial effector enzymes that transduce divergent signals from upstream receptor pathways and are responsible for catalyzing the conversion of ATP to cAMP. The ten AC isoforms are categorized into four main groups; the class III or calcium-inhibited family of ACs comprises AC5 and AC6. These enzymes are very closely related in structure and have a paucity of selective activators or inhibitors, making it difficult to distinguish them experimentally. AC5 and AC6 are highly expressed in the heart and vasculature, as well as the spinal cord and brain; AC6 is also abundant in the lungs, kidney, and liver. However, while AC5 and AC6 have similar expression patterns with some redundant functions, they have distinct physiological roles due to differing regulation and cAMP signaling compartmentation. AC5 is critical in cardiac and vascular function; AC6 is a key effector of vasodilatory pathways in vascular myocytes and is enriched in fetal/neonatal tissues. Expression of both AC5 and AC6 decreases in heart failure; however, AC5 disruption is cardio-protective, while overexpression of AC6 rescues cardiac function in cardiac injury. This is a comprehensive review of the complex regulation of AC5 and AC6 in the cardiovascular system, highlighting overexpression and knockout studies as well as transgenic models illuminating each enzyme and focusing on post-translational modifications that regulate their cellular localization and biological functions. We also describe pharmacological challenges in the design of isoform-selective activators or inhibitors for AC5 and AC6, which may be relevant to developing new therapeutic approaches for several cardiovascular diseases.

Introduction: Hypoxic persistent pulmonary hypertension in the newborn (PPHN) is usually treated with oxygen and inhaled nitric oxide (NO), both pulmonary arterial relaxants. But treatment failure with NO occurs in 25% of cases. We previously demonstrated that 72 h exposure to hypoxia, modeling PPHN, sensitized pulmonary artery smooth muscle cells (PASMC) to the contractile agonist thromboxane and inhibited relaxant adenylyl cyclase (AC) activity.Methods: In this study, we examined the effects of sodium nitroprusside (SNP), as NO donor, on the thromboxane-mediated contraction and NO-independent relaxation pathways and on reactive oxygen species (ROS) accumulation in PASMC. In addition, we examined the effect of the peroxynitrite scavenger 5,10,15,20-Tetrakis (4-sulfonatophenyl)porphyrinato Iron (III) (FeTPPS) on these processes.Results: Exposure of PASMC to 72 h hypoxia increased total intracellular ROS compared to normoxic control cells and this was mitigated by treatment of cells with either SNP or FeTPPS. Total protein nitrosylation was increased in hypoxic PASMC compared to controls. Both normoxic and hypoxic cells treated with SNP exhibited increased total protein nitrosylation and intracellular nitrite; this was reduced by treatment with FeTPPS. While cell viability and mitochondrial number were unchanged by hypoxia, mitochondrial activity was decreased compared to controls; addition of FeTPPS did not alter this. Basal and maximal mitochondrial metabolism and ATP turnover were reduced in hypoxic PASMC compared to controls. Hypoxic PASMC had higher basal Ca2+, and a heightened peak Ca2+ response to thromboxane challenge compared to controls. Addition of SNP further elevated the peak Ca2+ response, while addition of FeTPPS brought peak Ca2+ response down to control levels. AC mediated relaxation was impaired in hypoxic PASMC compared to controls but was normalized following treatment with FeTPPS. Addition of SNP inhibited adenylyl cyclase activity in both normoxic and hypoxic PASMC. Moreover, addition of the Ca2+ chelator BAPTA improved AC activity, but the effect was minimal.Discussion: We conclude that NO independently augments contraction and inhibits relaxation pathways in hypoxic PASMC, in part by a mechanism involving nitrogen radical formation and protein nitrosylation. These observations may partially explain impaired effectiveness of NO when treating hypoxic pulmonary hypertension.