Activation of renal outer medullary potassium channel in the renal distal convoluted tubule by high potassium diet / 生理学报

Renal outer medullary potassium (ROMK) channel is an important K+ excretion channel in the body, and K+ secreted by the ROMK channels is most or all source of urinary potassium. Previous studies focused on the ROMK channels of thick ascending limb (TAL) and collecting duct (CD), while there were few studies on the involvement of ROMK channels of the late distal convoluted tubule (DCT2) in K+ excretion. The purpose of the present study was mainly to record the ROMK channels current in renal DCT2 and observe the effect of high potassium diet on the ROMK channels by using single channel and whole-cell patch-clamp techniques. The results showed that a small conductance channel current with a conductance of 39 pS could be recorded in the apical membrane of renal DCT2, and it could be blocked by Tertiapin-Q (TPNQ), a ROMK channel inhibitor. The high potassium diet significantly increased the probability of ROMK channel current occurrence in the apical membrane of renal DCT2, and enhanced the activity of ROMK channel, compared to normal potassium diet (P < 0.01). Western blot results also demonstrated that the high potassium diet significantly up-regulated the protein expression levels of ROMK channels and epithelial sodium channel (ENaC), and down-regulated the protein expression level of Na+-Cl- cotransporter (NCC). Moreover, the high potassium diet significantly increased urinary potassium excretion. These results suggest that the high potassium diet may activate the ROMK channels in the apical membrane of renal DCT2 and increase the urinary potassium excretion by up-regulating the expression of renal ROMK channels.

Effects of aquaporin 4 and inward rectifier potassium channel 4 1 on medullospinal edema after methylprednisolone treatment to suppress acute spinal cord injury in rat

Abstract Purpose: To investigate the effects of aquaporin 4 (AQP4) and inward rectifier potassium channel 4.1 (Kir4.1) on medullospinal edema after treatment with methylprednisolone (MP) to suppress acute spinal cord injury (ASCI) in rats. Methods: Sprague Dawley rats were randomly divided into control, sham, ASCI, and MP-treated ASCI groups. After the induction of ASCI, we injected 30 mg/kg MP via the tail vein at various time points. The Tarlov scoring method was applied to evaluate neurological symptoms, and the wet-dry weights method was applied to measure the water content of the spinal cord. Results: The motor function score of the ASCI group was significantly lower than that of the sham group, and the spinal water content was significantly increased. In addition, the levels of AQP4 and Kir4.1 were significantly increased, as was their degree of coexpression. Compared with that in the ASCI group, the motor function score and the water content were significantly increased in the MP group; in addition, the expression and coexpression of AQP4 and Kir4.1 were significantly reduced. Conclusion: Methylprednisolone inhibited medullospinal edema in rats with acute spinal cord injury, possibly by reducing the coexpression of aquaporin 4 and Kir4.1 in medullospinal tissues.

Tuberculosis in renal transplant patients: The experience of a single center in Medellín-Colombia, 2005-2013 / Tuberculose em pacientes transplantados renais: experiência de um único centro em Medellín-Colômbia, 2005-2013

Introduction: Tuberculosis is a common opportunistic infection in renal transplant patients. Objective: To obtain a clinical and laboratory description of transplant patients diagnosed with tuberculosis and their response to treatment during a period ranging from 2005 to 2013 at the Pablo Tobón Uribe Hospital. Methods: Retrospective and descriptive study. Results: In 641 renal transplants, tuberculosis was confirmed in 12 cases. Of these, 25% had a history of acute rejection, and 50% had creatinine levels greater than 1.5 mg/dl prior to infection. The disease typically presented as pulmonary (50%) and disseminated (33.3%). The first phase of treatment consisted of 3 months of HZRE (isoniazid, pyrazinamide, rifampicin and ethambutol) in 75% of the cases and HZME (isoniazid, pyrazinamide, moxifloxacin and ethambutol) in 25% of the cases. During the second phase of the treatment, 75% of the cases received isoniazid and rifampicin, and 25% of the cases received isoniazid and ethambutol. The length of treatment varied between 6 and 18 months. In 41.7% of patients, hepatotoxicity was associated with the beginning of anti-tuberculosis therapy. During a year-long follow-up, renal function remained stable, and the mortality rate was 16.7%. Conclusion: Tuberculosis in the renal transplant population studied caused diverse nonspecific symptoms. Pulmonary and disseminated tuberculosis were the most frequent forms and required prolonged treatment. Antituberculosis medications had a high toxicity and mortality. This infection must be considered when patients present with a febrile syndrome of unknown origin, especially during the first year after renal transplant. .

Introdução: A tuberculose é uma infecção oportunista comum em pacientes transplantados renais. Objetivo: Oferecer uma descrição clínica e laboratorial de pacientes transplantados com diagnóstico de tuberculose e sua resposta ao tratamento durante o período entre 2005 e 2013 no Hospital Pablo Tobón Uribe. Métodos: Estudo retrospectivo descritivo. Resultados: Em 641 transplantes renais, a tuberculose foi confirmada em 12 pacientes. Destes, 25% tinham histórico de rejeição aguda e 50% apresentaram níveis de creatinina superiores a 1,5 mg/dl antes da infecção. A patologia geralmente se apresentava como pulmonar (50%) e disseminada (33,3%). A primeira fase do tratamento consistiu de três meses de HZRE (isoniazida, pirazinamida, rifampicina e etambutol) em 75% dos casos e HZME (isoniazida, pirazinamida, moxifloxacina e etambutol) em 25% dos pacientes. Durante a segunda fase do tratamento, 75% dos pacientes receberam isoniazida e rifampicina e 25% isoniazida e etambutol. A duração do tratamento variou entre seis e 18 meses. Em 41,7% dos pacientes, hepatotoxicidade foi associada ao início do tratamento da tuberculose. Durante o seguimento de um ano a função renal manteve-se estável e a taxa de mortalidade foi de 16,7%. Conclusão: A tuberculose foi responsável por diversos sintomas inespecíficos na população de transplantados renais estudada. Tuberculose pulmonar e disseminada foram as formas mais frequentes de acometimento e necessitaram de tratamento prolongado. Medicamentos contra a tuberculose apresentaram alta toxicidade e mortalidade. Esta infecção deve ser considerada quando o paciente apresenta síndrome febril de origem desconhecida, especialmente durante o primeiro ano após o transplante renal. .