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Effects of aging and potassium depletion on renal collecting tubule K + ‐controlling ATPases
Author(s) -
EIAMONG SOMCHAI,
EIAMONG SOMCHIT,
SABATINI SANDRA
Publication year - 2002
Publication title -
nephrology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 61
eISSN - 1440-1797
pISSN - 1320-5358
DOI - 10.1046/j.1440-1797.2002.00088.x
Subject(s) - medicine , endocrinology , basal (medicine) , potassium , atpase , chemistry , enzyme , biochemistry , organic chemistry , insulin
SUMMARY: The effects of aging and potassium depletion (KD) on renal cortical and medullary collecting tubule (CCT and MCT) K + ‐controlling ATPase activities, Na + ,K + ‐ATPase and H + ,K + ‐ATPase, were performed in 4 and 30 month‐old male Fischer 344 x Brown‐Norway F1 (F344xBNF1) rate. Following KD, which was induced by a K + ‐deficient diet for 7 days, both animal age groups had comparable levels of hypokalaemia, but the decreased fractional excretion of K + (FEK + ) was more prominent in the old‐age group. the aged animals had a 37% lower basal Na + ,K + ‐ATPase activity in MCT ( P < 0.05), but marked increases in basal H + ,K + ‐ATPase activity in both CCT and MCT ( P <0.001) were noted. Potassium depletion resulted in 28% ( P <0.05) and 66% ( P <0.01) increases in CCT and MCT Na + ,K + ‐ATPase activities, respectively, in the young‐age group. In the old‐age group, KD caused a 125% ( P < 0.001) increase in MCT Na + ,K + ‐ATPase activity, but had no effect on CCT Na + ,K + ‐ATPase activity. the collecting tubule H + ,+‐ATPase activity was increased in both the young and old‐age KD groups. the increase of magnitude in the latter was much higher than in the former. In response to KD, the more prominent rises in CCT and MCT H + ,K + ‐ATPase activities (with an increased percentage in MCT Na + ,K + ‐ATPase activity) was observed in the old‐age animals when compared with the younger ones. This could result in an increased K + reabsorption, leading to the lower value of FEk + . Thus, the K + ‐controlling mechanisms in the renal collecting tubule of aging rats are still intact and effective in coping with KD.