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Renal Expression of an Ammonia Transporter in Rats with a Unilateral Ureteral Obstruction

일측성 요로폐쇄 흰쥐 신장에서 암모니아 운반체의 발현

  • Kim, Seung Jung (Department of Internal Medicine, Medical Research Institute, Chungbuk National University College of Medicine) ;
  • Kim, Hye-Young (Department of Internal Medicine, Medical Research Institute, Chungbuk National University College of Medicine) ;
  • Choi, Jae Hyun (Department of Internal Medicine, Medical Research Institute, Chungbuk National University College of Medicine) ;
  • Lee, Dong Hwa (Department of Internal Medicine, Medical Research Institute, Chungbuk National University College of Medicine) ;
  • Kim, Kyung Min (Department of Internal Medicine, Medical Research Institute, Chungbuk National University College of Medicine) ;
  • Kim, Sun Moon (Department of Internal Medicine, Medical Research Institute, Chungbuk National University College of Medicine) ;
  • Kwon, Soon Kil (Department of Internal Medicine, Medical Research Institute, Chungbuk National University College of Medicine) ;
  • Shin, Kyung Sub (Department of Laboratory Medicine, Chungbuk National University College of Medicine) ;
  • Kim, Kyung Sook (Clinical Pharmacy, Chungbuk National University College of Pharmacy)
  • 김승중 (충북대학교 의과대학 내과학교실, 의학연구소) ;
  • 김혜영 (충북대학교 의과대학 내과학교실, 의학연구소) ;
  • 최재현 (충북대학교 의과대학 내과학교실, 의학연구소) ;
  • 이동화 (충북대학교 의과대학 내과학교실, 의학연구소) ;
  • 김경민 (충북대학교 의과대학 내과학교실, 의학연구소) ;
  • 김선문 (충북대학교 의과대학 내과학교실, 의학연구소) ;
  • 권순길 (충북대학교 의과대학 내과학교실, 의학연구소) ;
  • 신경섭 (충북대학교 의과대학 진단검사의학과교실) ;
  • 김경숙 (충북대학교 약학대학 임상약학실)
  • Received : 2013.06.11
  • Accepted : 2013.08.19
  • Published : 2014.04.01

Abstract

Background/Aims: Urinary tract obstruction induces a form of renal tubular acidosis with a urinary acidification defect caused by decreasing net acid excretion, which is predominantly due to a decrease in urinary ammonia excretion. The present study examined whether this decrease is associated with changes in the renal expression of an ammonia transporter family member, Rh C glycoprotein (Rhcg), in rats with a unilateral ureteral obstruction. Methods: Male Sprague-Dawley rats underwent a 24-h unilateral ureteral obstruction. Rhcg expression was then evaluated by immunoblotting and immunohistochemistry. Cell height, total cellular expression, expression in the apical 25% of the cell, and % of total expression in the apical region were quantified by immunohistochemistry with quantitative morphometric analysis. Results: After 24 h of unilateral ureteral obstruction, the serum bicarbonate level and total urinary ammonia excretion were decreased. Both light microscopy and immunohistochemistry with quantitative morphometric analysis demonstrated that the total intensity of Rhcg expression was decreased in the obstructed kidneys, whereas Rhcg expression did not change in the cortical collecting duct (CCD) and outer medullary collecting duct (OMCD) of nonobstructed kidneys in rats with a 24-h unilateral ureteral obstruction. Conclusions: The rats with a unilateral ureteral obstruction showed decreased urinary ammonia excretion associated with decreased Rhcg expression in the CCD and OMCD. These changes suggest that the ammonia transporter Rhcg mediates a urinary acidification defect associated with unilateral ureteral obstruction.

목적: 일측 요로폐쇄는 요중 산배설이 감소하는 질환으로 대부분 요 암모니아 배설의 감소에 의한 것으로 알려져 있다. 본 연구는 일측 요로 폐쇄 흰쥐에서 산배설의 변화와 암모니아 운반체인 Rh C Glycoprotein (Rhcg)의 발현 변화를 확인하여 신세뇨관산증의 병인에 암모니아 운반체의 역할을 규명하고자 하였다. 방법: Sprague-Dawley계 웅성 흰쥐를 사용하였으며, 실험군은 24시간 일측 요로폐쇄를 유발시켰다. 대조군과 실험군은 대사케이지에 mineral oil을 처리하여 24시간 동안 요를 수집하였다. Rhcg의 면역조직화학염색을 시행하였고 세포크기, 총 Rhcg 발현, 자유세포면의 Rhcg 발현에 대하여 면역조직화학염색법을 정량화 분석하였다. 결과: 일측 요로폐쇄군에서 혈중 tCO2 농도는 대조군 $27.5{\pm}2.8mEq/L$에 비하여 실험군은 $25.2{\pm}1.0mEq/L$로 감소하였다(p < 0.05). 24시간 요 암모니아 배설은 대조군 0.38{\pm} 0.08 mmol에 비하여 실험군에서 $0.19{\pm}0.03mmol$로 요 암모니아 배설이 감소하였으며(p < 0.05), Urine pH는 양 군 간에 차이가 없어 일측성 요로폐쇄에 의해 신세뇨관산증이 유발되었음을 확인하였다. 반정량적 immunoblot 검사에서 Rhcg의 단백 발현은 양군 간에 유의한 차이가 없었다. 면역조직 화학염색과 정량화 분석 결과 일측 요로폐쇄군에서 Rhcg의 면역반응성은 비폐쇄부위 콩팥에서는 차이가 없었으나 폐쇄부위 콩팥에서는 감소하였다. 결론: 일측 요로폐쇄 흰쥐에서 암모니아 배설 감소와 폐쇄부위 콩팥에서 Rhcg의 면역반응성의 감소가 동반되었다. 따라서 일측 요로폐쇄의 산성화 장애 병인에 암모니아 운반체 Rhcg가 중요한 역할을 할 것으로 생각된다.

Keywords

References

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  1. Role of Ammonia Transporters in the Kidney with Ureteral Obstruction vol.86, pp.4, 2014, https://doi.org/10.3904/kjm.2014.86.4.442