The Role of 20-Hete in Mediating the Effect of Diatary K Intake on the Apical K Channels in the Mtal.

Hypertension ◽  
2000 ◽  
Vol 36 (suppl_1) ◽  
pp. 710-710
Author(s):  
WenHui Wang ◽  
RuiMin Gu ◽  
Yuan Wei ◽  
Michael Balazy ◽  
Houli Jiang
Keyword(s):  
K Channel ◽  
Thick Ascending Limb ◽  
Channel Activity ◽  
Patch Clamp Technique ◽  
Deficient Diet ◽  
K Channels ◽  
Medullary Thick Ascending Limb ◽  
A Value ◽  
High K

P95 We have used the patch clamp technique to study the effect of dietary-K intake on the apical K channels in the medullary thick ascending limb (mTAL) of rat kidneys. The channel activity, defined by NPo, of the 30 pS and 70 pS K channel was 0.18 and 0.11 in the mTAL from rats on a K-deficient diet, respectively. In contrast, NPo of the 30 pS and the 70 pS K channels increased to 0.60 and 0.80 in the tubules from animals on a high-K diet, respectively. We have also used GC/MC to measure the intracellular production of 20-hydroxyeicosanotetraenoic acid (20-HETE) in the mTAL. The concentration of 20-HETE was 0.8 pg/μg protein in the mTAL from rats on a high-K diet and increased significantly to 4.6 pg/μg protein in the tubules from rats on a K-deficient diet. Addition of N-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS) or 17-octadecynoic acid (17ODYA), agents which inhibit the formation of 20-HETE, had no significant effect on the activity of the 30 pS K channels. However, DDMS/17ODYA significantly increased the activity of the apical 70 pS K channel from 0.11 to 0.91 in the mTAL from rats on a K-deficient diet. In contrast, inhibition of the cytochrome P450 metabolism of arachidonic acid (AA) increased NPo from 0.64 to 0.81 in the tubules from animals on a high-K diet. Furthermore, the concentration of 20-HETE required to block the channel activity by 50% was the same in the mTAL from rats on a high K diet as that on a K-deficient diet. This indicates that the diminished response of the 70 pS K channel to the inhibition of P450 metabolism of AA is not the result of decreasing 20-HETE sensitivity in the mTAL from rats on a high K diet. Finally, the pretreatment of the tubules with DDMS increased NPo of the 70 pS K channels in the mTAL from rats on a K-deficient diet to 0.76, a value which is not significantly different from the NPo in the tubules from rats on a high-K diet. We conclude that an increase in 20-HETE production is involved in reducing the activity of the apical 70 pS K channels in the mTAL from rats on a K-deficient diet.

scholarly journals Role of 20-HETE in mediating the effect of dietary K intake on the apical K channels in the mTAL

2001 ◽  
Vol 280 (2) ◽  
pp. F223-F230 ◽  
Author(s):  
Ruimin Gu ◽  
Yuan Wei ◽  
Houli Jiang ◽  
Michael Balazy ◽  
Wenhui Wang
Keyword(s):  
Gas Chromatography Mass Spectrometry ◽  
K Channel ◽  
Thick Ascending Limb ◽  
Patch Clamp Technique ◽  
Open Probability ◽  
Deficient Diet ◽  
K Channels ◽  
Medullary Thick Ascending Limb ◽  
High K

We have used the patch-clamp technique to study the effect of dietary K intake on the apical K channels in the medullary thick ascending limb (mTAL) of rat kidneys. The channel activity, defined by the number of channels in a patch and the open probability ( NP o), of the 30- and 70-pS K channels, was 0.18 and 0.11, respectively, in the mTAL from rats on a K-deficient diet. In contrast, NP o of the 30- and 70-pS K channels increased to 0.60 and 0.80, respectively, in the tubules from animals on a high-K diet. The concentration of 20-hydroxyeicosatetraenoic acid (20-HETE) measured with gas chromatography-mass spectrometry was 0.8 pg/μg protein in the mTAL from rats on a high-K diet and increased significantly to 4.6 pg/μg protein in the tubules from rats on a K-deficient diet. Addition of N-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS) or 17-octadecynoic acid (17-ODYA), agents that inhibit the formation of 20-HETE, had no significant effect on the activity of the 30-pS K channels. However, DDMS/17-ODYA significantly increased the activity of the apical 70-pS K channel from 0.11 to 0.91 in the mTAL from rats on a K-deficient diet. In contrast, inhibition of the cytochrome P-450 metabolism of arachidonic acid increased NP o from 0.64 to 0.81 in the tubules from animals on a high-K diet. Furthermore, the sensitivity of the 70-pS K channel to 20-HETE was the same between rats on a high-K diet and on a K-deficient diet. Finally, the pretreatment of the tubules with DDMS increased NP o of the 70-pS K channels in the mTAL from rats on a K-deficient diet to 0.76. We conclude that an increase in 20-HETE production is involved in reducing the activity of the apical 70-pS K channels in the mTAL from rats on a K-deficient diet.

Two types of K+ channel in thick ascending limb of rat kidney

1994 ◽  
Vol 267 (4) ◽  
pp. F599-F605 ◽  
Author(s):  
W. H. Wang
Keyword(s):  
Apical Membrane ◽  
Rat Kidney ◽  
Inhibitory Effect ◽  
K Channel ◽  
Thick Ascending Limb ◽  
Channel Activity ◽  
Patch Clamp Technique ◽  
Open Probability ◽  
K Channels ◽  
Inside Out

We have used the patch-clamp technique to study the apical K+ channels in the thick ascending limb (TAL) of the rat kidney. Two types of K+ channels, a low-conductance and an intermediate-conductance K+ channel, were identified in both cell-attached and inside-out patches. We confirmed the previously reported intermediate-conductance K+ channel (72 pS), which is inhibited by millimolar cell ATP, acidic pH, Ba2+, and quinidine (4). We now report a second K+ channel in apical membrane of the TAL. The slope conductance of this low-conductance K+ channel is 30 pS, and its open probability is 0.80 in cell-attached patches. This channel is not voltage dependent, and application of 2 mM ATP in the bath inhibits channel activity in inside-out patches. In addition, 250 microM glyburide, an ATP-sensitive K+ channel inhibitor, blocks channel activity, whereas the same concentration of glyburide has no inhibitory effect on the 72-pS K+ channel. Channel activity of the 30-pS K+ channel decreases rapidly upon excision of patches (channel run down). Application of 0.1 mM ATP and the catalytic subunit of adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase A (PKA) restores channel activity. Furthermore, addition of 0.1 mM 8-(4-chlorophenylthio)-cAMP or 50-100 pM vasopressin in the cell-attached patches increases channel activity. In conclusion, two types of K+ channels are present in the apical membrane of TAL of rat kidney, and PKA plays an important role in modulation of the low-conductance K+ channel activity.

Arachidonic acid inhibits K channels in basolateral membrane of the thick ascending limb

2002 ◽  
Vol 283 (3) ◽  
pp. F407-F414 ◽  
Author(s):  
Rui-Min Gu ◽  
Wen-Hui Wang
Keyword(s):  
Arachidonic Acid ◽  
Basolateral Membrane ◽  
Inhibitory Effect ◽  
K Channel ◽  
Thick Ascending Limb ◽  
Channel Activity ◽  
Patch Clamp Technique ◽  
Open Probability ◽  
K Channels ◽  
Cytochrome P 450

We have used the patch-clamp technique to study the effect of arachidonic acid (AA) on the basolateral K channels in the medullary thick ascending limb (mTAL) of rat kidney. An inwardly rectifying 50-pS K channel was identified in cell-attached and inside-out patches in the basolateral membrane of the mTAL. The channel open probability ( P o) was 0.51 at the spontaneous cell membrane potential and decreased to 0.25 by 30 mV hyperpolarization. The addition of 5 μM AA decreased channel activity, identified as NP o, from 0.58 to 0.08 in cell-attached patches. The effect of AA on the 50-pS K channel was specific because 10 μM cis-11,14,17-eicosatrienoic acid had no significant effect on channel activity. To determine whether the effect of AA was mediated by AA per se or by its metabolites, we examined the effect of AA on channel activity in the presence of indomethacin, an inhibitor of cyclooxygenase, or N-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS), an inhibitor of cytochrome P-450 monooxygenase. Inhibition of cyclooxygenase increased channel activity from 0.54 to 0.9. However, indomethacin did not abolish the inhibitory effect of AA on the 50-pS K channel. In contrast, inhibition of cytochrome P-450 metabolism not only increased channel activity from 0.49 to 0.83 but also completely abolished the effect of AA. Moreover, addition of DDMS can reverse the inhibitory effect of AA on channel activity. The notion that the effect of AA was mediated by cytochrome P-450-dependent metabolites of AA is also supported by the observation that addition of 100 nM of 20-hydroxyeicosatetraenoic acid, a main metabolite of AA in the mTAL, can mimic the effect of AA. We conclude that AA inhibits the 50-pS K channel in the basolateral membrane of the mTAL and that the effect of AA is mainly mediated by cytochrome P-450-dependent metabolites of AA.

Phospholipase A2 is involved in mediating the effect of extracellular Ca2+ on apical K+ channels in rat TAL

1997 ◽  
Vol 273 (3) ◽  
pp. F421-F429 ◽  
Author(s):  
W. Wang ◽  
M. Lu ◽  
M. Balazy ◽  
S. C. Hebert
Keyword(s):  
Phospholipase A2 ◽  
Fluorescent Dyes ◽  
Rat Kidney ◽  
K Channel ◽  
Thick Ascending Limb ◽  
Channel Activity ◽  
Patch Clamp Technique ◽  
Acetoxymethyl Ester ◽  
K Channels ◽  
Stimulation Of

Raising extracellular Ca2+ (Ca2+o) stimulating the Ca(2+)-sensing receptor (CaR) decreased the activity of the apical 70-pS K+ channel via a cytochrome P-450-dependent mechanism in the thick ascending limb (TAL) of the rat kidney [W. H. Wang, M. Lu, and S. C. Hebert. Am. J. Physiol. 270 (Cell Physiol. 39): C103-C111, 1996]. We have now used the patch-clamp technique and fluorescent dyes to investigate the signaling mechanism by which this effect is produced. Addition of 500 microM gadolinium (Gd3+), an agent which has been shown to activate the CaR (E. M. Brown, G. Gamba, D. Riccardi, M. Lombardi, R. Butters, O. Kifor, A. Sun, M. A. Hediger, J. Lytton, and S. C. Hebert. Nature 366: 575-580, 1993), mimics the inhibitory effect of raising Ca2+o from 1.1 to 5 mM on channel activity. Effects of the high Ca2+o and Gd3+ were abolished by blockade of phospholipase A2 (PLA2) but not by inhibition of phospholipase C (PLC). Raising Ca2+o also increased 20-hydroxyeicosatetraenoic acid production significantly. To investigate the effect of stimulation of the CaR on intracellular Ca2+ (Ca2+i), we used the acetoxymethyl ester of fura 2 to monitor the Ca2+i. Raising Ca2+o from 1.1 to 5 mM increased the Ca2+i significantly from 50 to 150 nM. However, addition of thapsigargin failed to abolish the effect of 5 mM Ca2+o on Ca2+i. Also, application of Gd3+ only slightly increased the Ca2+i, suggesting that elevation of the Ca2+i by high Ca2+o was the result of an influx of Ca2+ rather than enhanced Ca2+ release from Ca2+ stores. That the increase in Ca2+ influx is not mainly responsible for the effect of stimulating the CaR on channel activity is further supported by experiments in which 500 microM Gd3+ inhibited the K+ channel in cell-attached patches in a Ca(2+)-free bath. Furthermore, addition of 500 microM Gd3+ or 5 mM Ca2+o decreased intracellular Na+ measured with fluorescent sodium indicator, suggesting inhibition of Na+ transport. We conclude that PLA2 is involved in the stimulation of the CaR-induced inhibition of apical K+ channels in the TAL.

Adenosine stimulates the basolateral 50 pS K channels in the thick ascending limb of the rat kidney

2007 ◽  
Vol 293 (1) ◽  
pp. F299-F305 ◽  
Author(s):  
Ruimin Gu ◽  
Jing Wang ◽  
Yunhong Zhang ◽  
Wennan Li ◽  
Ying Xu ◽  
...  
Keyword(s):  
Adenosine Receptor ◽  
Rat Kidney ◽  
Basolateral Membrane ◽  
K Channel ◽  
Thick Ascending Limb ◽  
Dependent Manner ◽  
Channel Activity ◽  
Patch Clamp Technique ◽  
K Channels ◽  
Adenosine Receptor Agonist

We used the patch-clamp technique to examine the effect of adenosine on the basolateral K channels in the thick ascending limb (TAL) of the rat kidney. A 50-pS inwardly rectifying K channel was detected in the basolateral membrane, and the channel activity was decreased by hyperpolarization. Application of adenosine (10 μM) increased the activity of basolateral 50 pS K channels, defined by NPo, from 0.21 to 0.41. The effect of adenosine on the 50 pS K channels was mimicked by cyclohexyladenosine (CHA), which increased channel activity by a dose-dependent manner. However, inhibition of the A1 adenosine receptor with 8-cyclopentyl-1, 3-dipropylxanthine (DPCPX) failed to block the effect of CHA. In contrast, application of 8-(3-chlorostyryl) caffeine (CSC), an A2 adenosine antagonist, abolished the stimulatory effect of CHA. The possibility that the effect of adenosine and adenosine analog on the basolateral 50 pS K channel was the result of activation of the A2 adenosine receptor was also suggested by the observation that application of CGS-21680, a selected A2A adenosine receptor agonist, increased the channel activity. Also, inhibition of PKA with N-[2-(methylamino)ethyl]-5-isoquinoline sulfonamide-2HC1 abolished the stimulatory effect of CHA on the basolateral 50 pS K channel. Moreover, addition of the membrane-permeable cAMP analog increases the activity of 50 pS K channels. We conclude that adenosine activates the 50 pS K channel in the basolateral membrane of the TAL and the stimulatory effect is mainly mediated by a PKA-dependent pathway via the A2 adenosine receptor in the TAL.

Ca2+-activated K+ channels in cultured medullary thick ascending limb cells

1987 ◽  
Vol 252 (2) ◽  
pp. C121-C127 ◽  
Author(s):  
S. E. Guggino ◽  
W. B. Guggino ◽  
N. Green ◽  
B. Sacktor
Keyword(s):  
Cell Membrane ◽  
Single Channel ◽  
Apical Cell ◽  
Outward Current ◽  
K Channel ◽  
Thick Ascending Limb ◽  
Patch Clamp Technique ◽  
Apical Cell Membrane ◽  
K Channels ◽  
Medullary Thick Ascending Limb

The conductive properties of a clone of medullary thick ascending limb (MTAL) cells (GRB-MAL1) were assessed using conventional microelectrodes and the patch clamp technique. The apical cell membrane potential (Va) of MTAL cells was -46 +/- 3 mV. Addition of Ba2+ (1 mM) to the apical solution induced a 22 +/- 2 mV depolarization of Va, whereas furosemide hyperpolarized Va by -5 +/- 1 mV. In the cell-attached patch configuration, the most frequently occurring channel had a single channel conductance of 121 +/- 5 pS and carried outward current. In excised patches, current movement was down the electrochemical K+ gradient. Fluctuations were activated by depolarization of Va and by increasing Ca2+ concentration on the intracellular face. Micromolar amounts of Ba2+ on the intracellular face of the membrane inhibited channel activity. We conclude that cultures of MTAL cells GRB-MAL1 retain at least two of the properties of the mature phenotype, namely, an apical K+ conductance and a sensitivity to loop diuretics; the most frequently occurring channel in the apical cell membrane is a Ca2+-activated, maxi-K+ channel; and, finally Ca2+-activated K+ channels may play a role in generating the apical K+ conductance in cultured MTAL cells.

scholarly journals Angiotensin II stimulates basolateral 50-pS K channels in the thick ascending limb

2014 ◽  
Vol 306 (5) ◽  
pp. F509-F516 ◽  
Author(s):  
Mingxiao Wang ◽  
Haiyan Luan ◽  
Peng Wu ◽  
Lili Fan ◽  
Lijun Wang ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Protein Tyrosine Kinase ◽  
Rat Kidney ◽  
K Channel ◽  
Thick Ascending Limb ◽  
Ang Ii ◽  
Channel Activity ◽  
Patch Clamp Technique ◽  
K Channels ◽  
Family Protein

We used the patch-clamp technique to examine the effect of angiotensin II (ANG II) on the basolateral K channels in the thick ascending limb (TAL) of the rat kidney. Application of ANG II increased the channel activity and the current amplitude of the basolateral 50-pS K channel. The stimulatory effect of ANG II on the K channels was completely abolished by losartan, an inhibitor of type 1 angiotensin receptor (AT1R), but not by PD123319, an AT2R antagonist. Moreover, inhibition of phospholipase C (PLC) and protein kinase C (PKC) also abrogated the stimulatory effect of ANG II on the basolateral K channels in the TAL. This suggests that the stimulatory effect of ANG II on the K channels was induced by activating PLC and PKC pathways. Western blotting demonstrated that ANG II increased the phosphorylation of c-Src at tyrosine residue 416, an indication of c-Src activation. This effect was mimicked by PKC stimulator but abolished by calphostin C. Moreover, inhibition of NADPH oxidase (NOX) also blocked the effect of ANG II on c-Src tyrosine phosphorylation. The role of Src-family protein tyrosine kinase (SFK) in mediating the effect of ANG II on the basolateral K channel was further suggested by the experiments in which inhibition of SFK abrogated the stimulatory effect of ANG II on the basolateral 50-pS K channel. We conclude that ANG II increases basolateral 50-pS K channel activity via AT1R and that activation of AT1R stimulates SFK by a PLC-PKC-NOX-dependent mechanism.

Nitric oxide increases the activity of the apical 70-pS K+ channel in TAL of rat kidney

1998 ◽  
Vol 274 (5) ◽  
pp. F946-F950 ◽  
Author(s):  
Ming Lu ◽  
Xiaohong Wang ◽  
Wenhui Wang
Keyword(s):  
Nitric Oxide ◽  
Rat Kidney ◽  
K Channel ◽  
Thick Ascending Limb ◽  
Channel Activity ◽  
Patch Clamp Technique ◽  
No Donor ◽  
Oxide Synthase ◽  
Dependent Pathway

We have previously shown that nitric oxide (NO) mediates the stimulatory effect of angiotensin II on the apical 70-pS K+ channel in the thick ascending limb (TAL) of Henle’s loop of the rat kidney (12). In the present study, we used the patch-clamp technique to examine the effects of NO on the 70-pS K+ channel. Addition of 10 μM S-nitroso- N-acetylpenicillamine (SNAP), a NO donor, increased the channel activity in cell-attached patches. In contrast, application of 100 μM N ω-nitro-l-arginine methyl ester (l-NAME), an inhibitor of nitric oxide synthase (NOS), reduced the channel activity by 75 ± 7%. The effect of l-NAME was the result of inhibiting NOS, since d-NAME, which does not block NOS activity, had no effect on the channel activity. In addition, the effect ofl-NAME was abolished in the presence of 1 mM l-arginine or by addition of 10 μM SNAP, further supporting the role of NO. Finally, the l-NAME-induced inhibition was also reversed by adding 8-bromoguanosine 3′,5′-cyclic monophosphate (8-BrcGMP). That the effect of NO is mediated by the cGMP-dependent pathway is also suggested by experiments in which inhibition of guanylate cyclase abolished the effect of SNAP. Finally, 10 μM SNAP significantly increased cGMP concentration of the medullary TAL from 12.4 fM/μg protein to 38.9 fM/μg protein, as measured with ELISA. We conclude that NO is involved in regulating the activity of the apical 70-pS K+ channel in the TAL of the rat kidney.

scholarly journals Stimulation of A2a adenosine receptor abolishes the inhibitory effect of arachidonic acid on the basolateral 50-pS K channel in the thick ascending limb

2011 ◽  
Vol 300 (4) ◽  
pp. F906-F913 ◽  
Author(s):  
Mingxiao Wang ◽  
Hongyu Sui ◽  
Wennan Li ◽  
Jing Wang ◽  
Yujie Liu ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Inhibitory Effect ◽  
K Channel ◽  
Thick Ascending Limb ◽  
Channel Activity ◽  
Patch Clamp Technique ◽  
A2a Adenosine Receptor ◽  
K Channels ◽  
Cgs 21680 ◽  
Stimulation Of

The basolateral 50-pS K channels are stimulated by a cAMP-dependent pathway and inhibited by cytochrome P-450-omega-hydroxylase-dependent metabolism of arachidonic acid (AA) in the rat thick ascending limb (TAL). We now used the patch-clamp technique to examine whether stimulation of adenosine A2a receptor modulates the inhibitory effect of AA on the basolateral 50-pS K channels in the medullary TAL. Stimulation of adenosine A2a receptor with CGS-21680 or inhibition of phospholipase A2 (PLA2) with AACOCF3 increased the 50-pS K channel activity in the TAL. Western blot demonstrated that application of CGS-21680 decreased the phosphorylation of PLA2 at serine residue 505, an indication of inhibiting PLA2 activity. In the presence of CGS-21680, inhibition of PLA2 had no further effect on the basolateral 50-pS K channels. The possibility that CGS-21680-induced stimulation of the basolateral 50-pS K channels was partially achieved by inhibition of PLA2 in the TAL was also supported by the observation that CGS-21680 had no additional effect in the presence of AACOCF3. Moreover, stimulation of adenosine A2a receptor with CGS-21680 also abolished the inhibitory effect of AA and 20-hydroxyeicosatetraenoic acid (20-HETE) on the 50-pS K channels. The effect of CGS-21680 on AA and 20-HETE-mediated inhibition of the 50-pS K channels was mediated by cAMP because application of membrane-permeable cAMP analog, dibutyryl-cAMP, not only increased the 50-pS K channel activity but also abolished the inhibitory effect of AA and 20-HETE. We conclude that stimulation of adenosine A2a receptor increased the 50-pS K channel activity in the TAL, an effect that is achieved by suppression of PLA2 activity and 20-HETE-induced inhibition.

scholarly journals K Depletion Enhances the Extracellular Ca2+-Induced Inhibition of the Apical K Channels in the Mtal of Rat Kidney

2001 ◽  
Vol 119 (1) ◽  
pp. 33-44 ◽  
Author(s):  
Rui-Min Gu ◽  
Yuan Wei ◽  
Ho-Lin Jiang ◽  
Dao-Hong Lin ◽  
Hyacinth Sterling ◽  
...  
Keyword(s):  
Rat Kidney ◽  
Inhibitory Effect ◽  
K Channel ◽  
Thick Ascending Limb ◽  
Channel Activity ◽  
Patch Clamp Technique ◽  
No Donor ◽  
P450 Monooxygenase ◽  
High K ◽  
K Depletion

We have shown previously that raising extracellular Ca2+ inhibited the apical 70-pS K channel in the thick ascending limb (TAL; Wang, W.H., M. Lu, and S.C. Hebert. 1996. Am. J. Physiol. 270:C103–C111). We now used the patch-clamp technique to study the effect of increasing the extracellular Ca2+ on the 70-pS K channel in the mTAL from rats on a different K diet. Increasing the extracellular Ca2+ from 10 μM to 0.5, 1, and to 1.5 mM in the mTAL from rats on a K-deficient (KD) diet inhibited the channel activity by 30, 65, and 90%, respectively. In contrast, raising the extracellular Ca2+ to 1.5 mM had no significant effect on channel activity in the mTAL from animals on a high K (HK) diet and further increasing the extracellular Ca2+ to 2.5, 3.5, and 5.5 mM decreased the channel activity by 29, 55, and 90%, respectively. Inhibition of the cytochrome P450 monooxygenase completely abolished the effect of the extracellular Ca2+ on channel activity in the mTAL from rats on a different K diet. In contrast, blocking cyclooxygenase did not significantly alter the responsiveness of the 70-pS K channel to the extracellular Ca2+. Moreover, addition of sodium nitropruside, a nitric oxide (NO) donor, not only increased the channel activity, but also blunted the inhibitory effect of the extracellular Ca2+ on the 70-pS K channel and decreased 20-hydroxyeicosatetraenoic acid (20-HETE) concentration in the mTAL from rats on a KD diet. In contrast, inhibiting NOS with L-NAME enhanced the inhibitory effect of the extracellular Ca2+ on the channel activity and increased 20-HETE concentration in the mTAL from rats on a high K diet. Western blot has further shown that the expression of inducible NO synthase (iNOS) is significantly higher in the renal medulla from rats on an HK diet than that on a KD diet. Also, addition of S-nitroso-N-acetylpenicillamine abolished the inhibitory effect of arachidonic acid on channel activity in the mTAL, whereas it did not block the inhibitory effect of 20-HETE. We conclude that a low dietary K intake increases the sensitivity of the 70-pS K channel to the extracellular Ca2+, and that a decrease in NOS activity is involved in enhancing the inhibitory effect of the extracellular Ca2+ on channel activity in the mTAL during K depletion.

Sign in / Sign up

Export Citation Format

Share Document