PMID- 8570863
OWN - NLM
STAT- MEDLINE
DCOM- 19960301
LR  - 20190515
IS  - 0886-022X (Print)
IS  - 0886-022X (Linking)
VI  - 17
IP  - 5
DP  - 1995 Sep
TI  - Induced alterations in calcium uptake rate in normoxic rate proximal tubules.
PG  - 503-15
AB  - This study is well-oxygenated, freshly isolated rat proximal tubules (RPT), 
      examined the effects of several drugs that alter the transmembrane K+ and Na+ 
      gradients across cell membranes, including valinomycin (VAL), amphotericin B 
      (AMPHO), and ouabain (OUAB). The effects of high extracellular potassium chloride 
      (KCl) concentrations (45 mM) and low extracellular sodium concentration (100mM) 
      were also studied. After 10 min of drug exposure Ca2+ uptake rate (nmol/mg/min) 
      increased from 2.7 to 3.8 with VAL (p < .02), from 2.9 to 3.7 with AMPHO (p < 
      .05), from 3.6 to 4.1 with OUAB (p < .05), and from 3.2 to 4.8 with 45 mM KCl (p 
      < .001). Ca2+ uptake rate was sustained at these high levels at 20 min in all 
      treated RPT except those exposed to OUAB. LDH release averaged less than 15% in 
      control tubules and did not increase significantly except in RPT treated with 
      VAL, where LDH release at 10 min was 48% and at 20 min was 57% (both p < .001). 
      Of importance, only in VAL-treated RPT did ATP decrease to low levels (6.7 
      nmol/mg in control to 2.0 +/- 0.3 nmol/mg in VAL, p < .001). Treatment with 
      verapamil reduced Ca2+ uptake rates at 10 min in VAL-treated RPT (from 3.8 to 
      3.1, p < .02, in AMPHO-treated RPT (from 3.8 to 3.1 p < .001), in OUAB-treated 
      tubules (from 4.0 to 3.4, p < .01), and in KCl-treated RPT (from 3.7 to 3.2, p < 
      .01). These results indicate that acute changes in the transmembrane ion gradient 
      in RPT are accompanied by increased Ca2+ uptake rates. Ca2+ uptake rates are also 
      increased during O2 deprivation in RPT, a situation in which the transmembrane 
      ion gradient is likewise altered. The increased Ca2+ uptake rate observed in the 
      present study and during hypoxia may have a common basis, that is, altered 
      transmembrane ion gradients or some function thereof.
FAU - Burke, T J
AU  - Burke TJ
AD  - Department of Medicine, University of Colorado School of Medicine, Denver 80262, 
      USA.
FAU - Joseph, J K
AU  - Joseph JK
FAU - Bunnachak, D
AU  - Bunnachak D
FAU - Almeida, A
AU  - Almeida A
FAU - Wetzels, J F
AU  - Wetzels JF
FAU - Yu, L
AU  - Yu L
FAU - Kribben, A
AU  - Kribben A
FAU - Wieder, E
AU  - Wieder E
FAU - Schrier, R W
AU  - Schrier RW
LA  - eng
GR  - 35098/PHS HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - England
TA  - Ren Fail
JT  - Renal failure
JID - 8701128
RN  - 0 (Ionophores)
RN  - 2001-95-8 (Valinomycin)
RN  - 5ACL011P69 (Ouabain)
RN  - 7XU7A7DROE (Amphotericin B)
RN  - 8L70Q75FXE (Adenosine Triphosphate)
RN  - 9NEZ333N27 (Sodium)
RN  - EC 1.1.1.27 (L-Lactate Dehydrogenase)
RN  - RWP5GA015D (Potassium)
RN  - SY7Q814VUP (Calcium)
SB  - IM
MH  - Adenosine Triphosphate/metabolism
MH  - Amphotericin B/pharmacology
MH  - Animals
MH  - Calcium/*metabolism
MH  - Cell Membrane Permeability/drug effects/*physiology
MH  - In Vitro Techniques
MH  - Ionophores/pharmacology
MH  - Kidney Tubules, Proximal/cytology/drug effects/*metabolism
MH  - L-Lactate Dehydrogenase/drug effects/metabolism
MH  - Male
MH  - Membrane Potentials/drug effects
MH  - Ouabain/pharmacology
MH  - Potassium/metabolism
MH  - Rats
MH  - Rats, Sprague-Dawley
MH  - Sodium/metabolism
MH  - Valinomycin/pharmacology
EDAT- 1995/09/01 00:00
MHDA- 1995/09/01 00:01
CRDT- 1995/09/01 00:00
PHST- 1995/09/01 00:00 [pubmed]
PHST- 1995/09/01 00:01 [medline]
PHST- 1995/09/01 00:00 [entrez]
AID - 10.3109/08860229509037615 [doi]
PST - ppublish
SO  - Ren Fail. 1995 Sep;17(5):503-15. doi: 10.3109/08860229509037615.