H-K-ATPase enhancement of Rb efflux by cortical collecting duct

Xiaoming Zhou; Charles S. Wingo

H-K-ATPase enhancement of Rb efflux by cortical collecting duct

Xiaoming Zhou, Charles S. Wingo^*

^*Corresponding author for this work

Medicine

Research output: Contribution to journal › Article › peer-review

41 Scopus citations

Abstract

Previous studies suggest that enhancement of rubidium tracer (⁸⁶Rb) lumen-to-bath efflux following removal of luminal Na is mediated in part by a Ba-insensitive pathway. To determine the role of a primary active K pump in this response, we examined the action of known inhibitors of H-K-ATPase (Sch 28080) and Na-K-ATPase (ouabain) on the ⁸⁶Rb lumen-to-bath efflux coefficient (K_Rb). Luminal Sch 28080 (10 μM) significantly reduced K_Rb by 39 ± 8.0% (P < 0.05), whereas luminal ouabain (0.1 mM) reduced K_Rb by 10 ± 14% (P = not significant), suggesting that a luminal H-K-ATPase mediates Rb efflux. To examine whether H-K-ATPase mediates the increase in K_Rb following removal of luminal Na, additional experiments were conducted to examine the effect of Sch 28080 on K_Rb in the presence and the absence of luminal Na. In the presence of luminal Na, 10 μM Sch 28080 reduced K_Rb by 15 ± 5.0%. However, in the absence of luminal Na, 10 μM Sch 28080 decreased K_Rb by 48 ± 8.2%. The percentage inhibition of K_Rb by Sch 28080 was significantly greater in the absence of luminal Na than in its presence (P < 0.01), suggesting that the enhancement of K_Rb following removal of luminal Na is mediated in part by an H-K-ATPase pathway. In either case transepithelial voltage was not significantly altered. In contrast to the lack of effect of luminal ouabain, addition of 0.1 mM ouabain to the bath increased K_Rb (69.8 ± 11.1 vs. 95.9 ± 18.7 nm/s, P < 0.05). However, this effect of ouabain on K_Rb was totally abolished by perfusion of the cortical collecting duct (CCD) in the presence of 10 μM luminal Sch 28080 (69.8 ± 14.0 nm/s, basal period; 69.6 ± 14.1 nm/s, ouabain period). These data are consistent with the following conclusions, at least during K restriction: 1) H-K-ATPase is responsible for Rb (K) absorption in the rabbit CCD, 2) the presence of luminal Na reduces Rb (K) absorption by an H-K-ATPase-mediated mechanism, and 3) basolateral ouabain addition stimulates Rb (K) absorption via H-K-ATPase.

Original language	English
Pages (from-to)	F43-F48
Journal	American Journal of Physiology - Renal Fluid and Electrolyte Physiology
Volume	263
Issue number	1 32-1
State	Published - Jul 1992

Keywords

Acidification
Microperfusion
Potassium
Potassium absorption
Sch 28080
Sodium-potassium-adenosinetriphosphatase

Cite this

@article{bf582a31ea0a470aa3dd2ffa6ac10df0,

title = "H-K-ATPase enhancement of Rb efflux by cortical collecting duct",

abstract = "Previous studies suggest that enhancement of rubidium tracer (86Rb) lumen-to-bath efflux following removal of luminal Na is mediated in part by a Ba-insensitive pathway. To determine the role of a primary active K pump in this response, we examined the action of known inhibitors of H-K-ATPase (Sch 28080) and Na-K-ATPase (ouabain) on the 86Rb lumen-to-bath efflux coefficient (KRb). Luminal Sch 28080 (10 μM) significantly reduced KRb by 39 ± 8.0% (P < 0.05), whereas luminal ouabain (0.1 mM) reduced KRb by 10 ± 14% (P = not significant), suggesting that a luminal H-K-ATPase mediates Rb efflux. To examine whether H-K-ATPase mediates the increase in KRb following removal of luminal Na, additional experiments were conducted to examine the effect of Sch 28080 on KRb in the presence and the absence of luminal Na. In the presence of luminal Na, 10 μM Sch 28080 reduced KRb by 15 ± 5.0%. However, in the absence of luminal Na, 10 μM Sch 28080 decreased KRb by 48 ± 8.2%. The percentage inhibition of KRb by Sch 28080 was significantly greater in the absence of luminal Na than in its presence (P < 0.01), suggesting that the enhancement of KRb following removal of luminal Na is mediated in part by an H-K-ATPase pathway. In either case transepithelial voltage was not significantly altered. In contrast to the lack of effect of luminal ouabain, addition of 0.1 mM ouabain to the bath increased KRb (69.8 ± 11.1 vs. 95.9 ± 18.7 nm/s, P < 0.05). However, this effect of ouabain on KRb was totally abolished by perfusion of the cortical collecting duct (CCD) in the presence of 10 μM luminal Sch 28080 (69.8 ± 14.0 nm/s, basal period; 69.6 ± 14.1 nm/s, ouabain period). These data are consistent with the following conclusions, at least during K restriction: 1) H-K-ATPase is responsible for Rb (K) absorption in the rabbit CCD, 2) the presence of luminal Na reduces Rb (K) absorption by an H-K-ATPase-mediated mechanism, and 3) basolateral ouabain addition stimulates Rb (K) absorption via H-K-ATPase.",

keywords = "Acidification, Microperfusion, Potassium, Potassium absorption, Sch 28080, Sodium-potassium-adenosinetriphosphatase",

author = "Xiaoming Zhou and Wingo, {Charles S.}",

year = "1992",

month = jul,

language = "English",

volume = "263",

pages = "F43--F48",

journal = "American Journal of Physiology - Renal Fluid and Electrolyte Physiology",

issn = "0363-6127",

number = "1 32-1",

}

TY - JOUR

T1 - H-K-ATPase enhancement of Rb efflux by cortical collecting duct

AU - Zhou, Xiaoming

AU - Wingo, Charles S.

PY - 1992/7

Y1 - 1992/7

N2 - Previous studies suggest that enhancement of rubidium tracer (86Rb) lumen-to-bath efflux following removal of luminal Na is mediated in part by a Ba-insensitive pathway. To determine the role of a primary active K pump in this response, we examined the action of known inhibitors of H-K-ATPase (Sch 28080) and Na-K-ATPase (ouabain) on the 86Rb lumen-to-bath efflux coefficient (KRb). Luminal Sch 28080 (10 μM) significantly reduced KRb by 39 ± 8.0% (P < 0.05), whereas luminal ouabain (0.1 mM) reduced KRb by 10 ± 14% (P = not significant), suggesting that a luminal H-K-ATPase mediates Rb efflux. To examine whether H-K-ATPase mediates the increase in KRb following removal of luminal Na, additional experiments were conducted to examine the effect of Sch 28080 on KRb in the presence and the absence of luminal Na. In the presence of luminal Na, 10 μM Sch 28080 reduced KRb by 15 ± 5.0%. However, in the absence of luminal Na, 10 μM Sch 28080 decreased KRb by 48 ± 8.2%. The percentage inhibition of KRb by Sch 28080 was significantly greater in the absence of luminal Na than in its presence (P < 0.01), suggesting that the enhancement of KRb following removal of luminal Na is mediated in part by an H-K-ATPase pathway. In either case transepithelial voltage was not significantly altered. In contrast to the lack of effect of luminal ouabain, addition of 0.1 mM ouabain to the bath increased KRb (69.8 ± 11.1 vs. 95.9 ± 18.7 nm/s, P < 0.05). However, this effect of ouabain on KRb was totally abolished by perfusion of the cortical collecting duct (CCD) in the presence of 10 μM luminal Sch 28080 (69.8 ± 14.0 nm/s, basal period; 69.6 ± 14.1 nm/s, ouabain period). These data are consistent with the following conclusions, at least during K restriction: 1) H-K-ATPase is responsible for Rb (K) absorption in the rabbit CCD, 2) the presence of luminal Na reduces Rb (K) absorption by an H-K-ATPase-mediated mechanism, and 3) basolateral ouabain addition stimulates Rb (K) absorption via H-K-ATPase.

AB - Previous studies suggest that enhancement of rubidium tracer (86Rb) lumen-to-bath efflux following removal of luminal Na is mediated in part by a Ba-insensitive pathway. To determine the role of a primary active K pump in this response, we examined the action of known inhibitors of H-K-ATPase (Sch 28080) and Na-K-ATPase (ouabain) on the 86Rb lumen-to-bath efflux coefficient (KRb). Luminal Sch 28080 (10 μM) significantly reduced KRb by 39 ± 8.0% (P < 0.05), whereas luminal ouabain (0.1 mM) reduced KRb by 10 ± 14% (P = not significant), suggesting that a luminal H-K-ATPase mediates Rb efflux. To examine whether H-K-ATPase mediates the increase in KRb following removal of luminal Na, additional experiments were conducted to examine the effect of Sch 28080 on KRb in the presence and the absence of luminal Na. In the presence of luminal Na, 10 μM Sch 28080 reduced KRb by 15 ± 5.0%. However, in the absence of luminal Na, 10 μM Sch 28080 decreased KRb by 48 ± 8.2%. The percentage inhibition of KRb by Sch 28080 was significantly greater in the absence of luminal Na than in its presence (P < 0.01), suggesting that the enhancement of KRb following removal of luminal Na is mediated in part by an H-K-ATPase pathway. In either case transepithelial voltage was not significantly altered. In contrast to the lack of effect of luminal ouabain, addition of 0.1 mM ouabain to the bath increased KRb (69.8 ± 11.1 vs. 95.9 ± 18.7 nm/s, P < 0.05). However, this effect of ouabain on KRb was totally abolished by perfusion of the cortical collecting duct (CCD) in the presence of 10 μM luminal Sch 28080 (69.8 ± 14.0 nm/s, basal period; 69.6 ± 14.1 nm/s, ouabain period). These data are consistent with the following conclusions, at least during K restriction: 1) H-K-ATPase is responsible for Rb (K) absorption in the rabbit CCD, 2) the presence of luminal Na reduces Rb (K) absorption by an H-K-ATPase-mediated mechanism, and 3) basolateral ouabain addition stimulates Rb (K) absorption via H-K-ATPase.

KW - Acidification

KW - Microperfusion

KW - Potassium

KW - Potassium absorption

KW - Sch 28080

KW - Sodium-potassium-adenosinetriphosphatase

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M3 - Article

C2 - 1322055

AN - SCOPUS:0026740978

SN - 0363-6127

VL - 263

SP - F43-F48

JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology

JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology

IS - 1 32-1

ER -

H-K-ATPase enhancement of Rb efflux by cortical collecting duct

Abstract

Keywords

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