RESUMEN
OBJECTIVE: Increased breathing rate, apnea, and respiratory failure are associated with sudden unexpected death in epilepsy (SUDEP). We recently demonstrated the progressive nature of epilepsy and mortality in Kcna1-/- mice, a model of temporal lobe epilepsy and SUDEP. Here we tested the hypothesis that respiratory dysfunction progresses with age in Kcna1-/- mice, thereby increasing risk of respiratory failure and sudden death (SD). METHODS: Respiratory parameters were determined in conscious mice at baseline and following increasing doses of methacholine (MCh) using noninvasive airway mechanics (NAM) systems. Kcna1+/+ , Kcna1+/- , and Kcna1-/- littermates were assessed during 3 age ranges when up to ~30%, ~55%, and ~90% of Kcna1-/- mice have succumbed to SUDEP: postnatal day (P) 32-36, P40-46, and P48-56, respectively. Saturated arterial O2 (SaO2 ) was determined with pulse oximetry. Lung and brain tissues were isolated and Kcna1 gene and protein expression were evaluated by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) and Western blot techniques. Airway smooth muscle responsiveness was assessed in isolated trachea exposed to MCh. RESULTS: Kcna1-/- mice experienced an increase in basal respiratory drive, chronic oxygen desaturation, frequent apnea-hypopnea (A-H), an atypical breathing sequence of A-H-tachypnea-A-H, increased tidal volume, and hyperventilation induced by MCh. The MCh-provoked hyperventilation was dramatically attenuated with age. Of interest, only Kcna1-/- mice developed seizures following exposure to MCh. Seizures were provoked by lower concentrations of MCh as Kcna1-/- mice approached SD. MCh-induced seizures experienced by a subset of younger Kcna1-/- mice triggered death. Respiratory parameters of these younger Kcna1-/- mice resembled older near-SD Kcna1-/- mice. Kcna1 gene and protein were not expressed in Kcna1+/+ and Kcna1+/- lungs, and MCh-mediated airway smooth muscle contractions exhibited similar half-maximal effective concentration( EC50 ) in isolated Kcna1+/+ and Kcna1-/- trachea. SIGNIFICANCE: The Kcna1-/- model of SUDEP exhibits progressive respiratory dysfunction, which suggests a potential increased susceptibility for respiratory failure during severe seizures that may result in sudden death.
Asunto(s)
Apnea/genética , Muerte Súbita , Epilepsia del Lóbulo Temporal/fisiopatología , Hipoxia/genética , Canal de Potasio Kv.1.1/genética , Insuficiencia Respiratoria/genética , Animales , Apnea/complicaciones , Apnea/metabolismo , Broncoconstrictores/farmacología , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Epilepsia , Epilepsia del Lóbulo Temporal/complicaciones , Expresión Génica , Hiperventilación/inducido químicamente , Hipoxia/complicaciones , Hipoxia/metabolismo , Canal de Potasio Kv.1.1/metabolismo , Cloruro de Metacolina/farmacología , Ratones , Ratones Noqueados , Músculo Liso/efectos de los fármacos , Insuficiencia Respiratoria/complicaciones , Insuficiencia Respiratoria/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Taquipnea/complicaciones , Taquipnea/genética , Taquipnea/metabolismo , Volumen de Ventilación Pulmonar , Tráquea/efectos de los fármacosRESUMEN
Congenital protein C deficiency is an inherited coagulation disorder associated with an elevated risk of venous thromboembolism. A Saudi Arabian male from a consanguineous family was admitted to neonatal intensive care unit in his first days of life because of transient tachypnea and hematuria. Laboratory investigations determined low platelet and protein C deficiency. Direct sequencing of PROC gene and RNA analysis were performed. Analysis of factor V Leiden (G1691A) and factor II (G20210A) mutations was also done. Novel homozygous splice site mutation c.796+3A>T was detected in the index case and segregation was confirmed in the family. RNA analysis revealed the pathogenicity of the mutation by skipping exon 8 of PROC gene and changing the donor splice site of the exon. Detection of the molecular cause of protein C deficiency reduces life threatening and facilitates inductive carrier testing, prenatal and preimplantation genetic diagnosis for families.
Asunto(s)
Hematuria/genética , Mutación , Deficiencia de Proteína C/genética , Proteína C/genética , Sitios de Empalme de ARN , Taquipnea/genética , Secuencia de Bases , Plaquetas/metabolismo , Plaquetas/patología , Consanguinidad , Exones , Factor V/genética , Expresión Génica , Hematuria/sangre , Hematuria/congénito , Homocigoto , Humanos , Recién Nacido , Intrones , Masculino , Linaje , Recuento de Plaquetas , Deficiencia de Proteína C/sangre , Deficiencia de Proteína C/congénito , Protrombina/genética , Arabia Saudita , Taquipnea/sangre , Taquipnea/congénitoRESUMEN
C57BL6 mice display non-eupneic breathing and spontaneous apneas during wakefulness and sleep as well as markedly disordered breathing following cessation of a hypoxic challenge. We examined whether (1) C57BL6 mice display marked non-eupneic breathing following hypercapnic or hypoxic-hypercapnic challenges, and (2) compared the post-hypoxia changes in non-eupneic breathing of C57BL6 mice to those of B6AF1 (57BL6 dam × A/J sire) and Swiss-Webster mice, which display different ventilatory responses than C57BL6 mice. C57BL6 mice displayed marked increases in respiratory frequency and non-eupneic breathing upon return to room-air after hypoxic (10% O2, 90% N2), hypercapnic (5% CO2, 21% O2 and 74% N2) and hypoxic-hypercapnic (10% O2, 5% CO2 and 85% N2) challenges. B6AF1 mice displayed less tachypnea and reduced non-eupneic breathing post-hypoxia, whereas Swiss-Webster mice displayed robust tachypnea with minimal increases in non-eupneic breathing post-hypoxia. These studies demonstrate that non-eupneic breathing increases after physiologically-relevant hypoxic-hypercapnic challenge in C57BL6 mice and suggest that further studies with these and B6AF1 and Swiss-Webster mice will help define the genetics of non-eupneic breathing.
