Contribution of calcium‐activated potassium channels to the vasodilator effect of bradykinin in the isolated, perfused kidney of the rat

Rapacon, M.; Mieyal, Paul A.; McGiff, John C.; Fulton, David

doi:10.1111/j.1476-5381.1996.tb15566.x

Cited by 34 publications

(20 citation statements)

References 14 publications

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“…Non-speci®c eects of the inhibitors seem unlikely since SNP-induced relaxation was unchanged. Present results are in accordance with the mechanisms previously proposed for BK and/or ACh regarding the renal vasculature but also for perfused coronary arteries and various other vessels (Rapacon et al, 1996;Mombouli & Vanhoutte, 1997;Quilley et al, 1997;Mieyal et al, 1998). Moreover, since speci®c inhibitors respectively for large and small conductance Ca 2+ -activated K + channels, iberiotoxin and leiurotoxin, have been reported to be inactive on BK NO-independent renal vasodilation and since charybdotoxin inhibits both large and intermediate conductance Ca…”

Section: Discussionsupporting

confidence: 93%

“…-activated K + channels, present results favour a prominent contribution of intermediate conductance channels (Rapacon et al, 1996). K + channels are present in both endothelial and vascular smooth muscle cells (Himmel et al, 1993;Nelson & Quayle, 1995) and hyperpolarization can be induced by BK in endothelial cells (BeÂ ny & Chabaud, 1996).…”

Section: +mentioning

confidence: 53%

“…BK-induced vasodilation was mimicked by Tyr(Me) 8 BK, a selective B 2 receptor agonist (Regoli & BarabeÂ , 1980), and was inhibited by icatibant, a speci®c B 2 receptor antagonist. The question of kinin signalling pathways in renal vessels was previously addressed using BK (Fulton et al, 1992;Rapacon et al, 1996;Mieyal et al, 1998). The aim of the present study was to investigate these pathways in the isolated perfused rat kidney, with Tyr(Me) 8 BK.…”

Section: Introductionmentioning

confidence: 99%

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Signal transduction pathways involved in kinin B₂ receptor‐mediated vasodilation in the rat isolated perfused kidney

Bagaté

Grima

Imbs

et al. 2001

British J Pharmacology

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1 The signal transduction pathways involved in kinin B 2 receptor-related vasodilation were investigated in rat isolated perfused kidneys. During prostaglandin F 2a or KCl-induced constriction, the vasodilator response to a selective B 2 receptor agonist, Tyr(Me) BK by more than 60%, while inhibition of the cannabinoid CB 1 receptor (SR 141716A) had only a moderate eect. 5 Acetylcholine induced a concentration-dependent relaxation with characteristics nearly similar to the response to Tyr(Me) 8 BK. In contrast, the relaxation elicited by sodium nitroprusside was potentiated in the absence of NO (L-NOARG or removal of endothelium) but remained unchanged otherwise. 6 These results indicate that the activation of kinin B 2 receptors in the rat isolated kidney elicits an endothelium-dependent vasorelaxation, mainly dependent on the activation of charybdotoxinsensitive Ca 2+ -activated K + channels. In addition, cytochrome P450 derivatives appear to be involved.

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Section: Discussionsupporting

confidence: 93%

Section: +mentioning

confidence: 53%

Section: Introductionmentioning

confidence: 99%

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Signal transduction pathways involved in kinin B₂ receptor‐mediated vasodilation in the rat isolated perfused kidney

Bagaté

Grima

Imbs

et al. 2001

British J Pharmacology

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“…The human intermediate conductance K Ca channel, hIK1, is required for a variety of physiological processes including transepithelial ion transport (2)(3)(4)(5), vasodilation (6,7), T cell activation (8,9), cell proliferation (9 -11), and regulatory volume decrease (9,10). In addition to demonstrating modulation by intracellular Ca 2ϩ , we and others have demonstrated that hIK1 activity can be dynamically regulated by phosphorylation (1,9,(12)(13)(14).…”

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confidence: 90%

ATP-dependent Activation of the Intermediate Conductance, Ca2+-activated K+ Channel, hIK1, Is Conferred by a C-terminal Domain

Gerlach

Syme

Giltinan

et al. 2001

Journal of Biological Chemistry

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We previously demonstrated that hIK1 is activated directly by ATP in excised, inside-out patches in a protein kinase A inhibitor 5-24 dependent manner, suggesting a role for phosphorylation in the regulation of this Ca 2؉ -dependent channel. However, mutation of the single consensus cAMP-dependent protein kinase phosphorylation site (S334A) failed to modify the response of hIK1 to ATP (Gerlach, A. C., Gangopadhyay, N. N., and Devor, D. C. (2000) J. Biol. Chem. 275, 585-598). Here we demonstrate that ATP does not similarly activate the highly homologous Ca 2؉ -dependent K ؉ channels, hSK1, rSK2, and rSK3. To define the region of hIK1 responsible for the ATP-dependent regulation, we generated a series of hIK1 truncations and hIK1/rSK2 chimeras. ATP did not activate a chimera containing the N terminus plus S1-S4 from hIK1. In contrast, ATP activated a chimera containing the hIK1 C-terminal amino acids His 299 -Lys 427 . Furthermore, truncation of hIK1 at Leu 414 resulted in an ATP-dependent channel, whereas larger truncations of hIK1 failed to express. Additional hIK1/ rSK2 chimeras defined the minimal region of hIK1 required to confer complete ATP sensitivity as including amino acids Arg 355 -Ala 413 . An alanine scan of all nonconserved serines and threonines within this region failed to alter the response of hIK1 to ATP, suggesting that hIK1 itself is not directly phosphorylated. Additionally, substitution of amino acids Arg 355 -Met 368 of hIK1 into the corresponding region of rSK2 resulted in an ATP-dependent activation, which was ϳ50% of that of hIK1. These results demonstrate that amino acids Arg 355 -Ala 413 within the C terminus of hIK1 confer sensitivity to ATP. Finally, we demonstrate that the ATPdependent phosphorylation of hIK1 or an associated protein is independent of Ca 2؉ .The human intermediate conductance K Ca channel, hIK1, is required for a variety of physiological processes including transepithelial ion transport (2-5), vasodilation (6, 7), T cell activation (8, 9), cell proliferation (9 -11), and regulatory volume decrease (9, 10). In addition to demonstrating modulation by intracellular Ca 2ϩ , we and others have demonstrated that hIK1 activity can be dynamically regulated by phosphorylation (1,9,(12)(13)(14). Several of these studies have demonstrated an ATP-dependent activation of hIK1 in excised, inside-out membrane patches that can be reversed by exogenous phosphatases and/or kinase inhibitors (1,12,13). Based on these observations, we speculated that the phosphorylation-dependent modulation of hIK1 plays a critical role in modulating the physiological processes in which hIK1 is involved.In our previous study we demonstrated, in excised, insideout patches, that addition of ATP (1 mM) resulted in, on average, a 3-fold increase in hIK1 activity (1), having an EC 50 of 50 M.1 The stimulatory effect of ATP exhibited a slow onset, requiring several minutes for the maximal response, was strictly Mg 2ϩ -dependent, and could be mimicked by neither hydrolyzeable (ADP, GTP, UTP, CTP, ITP) nor non-...

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“…IK channels have also been implicated in the microvasculature of the kidney, where they may be responsible for the vasodilatory effects of bradykinin (14). In brain capillary endothelial cells, IK channels, activated by endothelin that is produced by neurons and glia, shunt excess K ϩ into the blood (15).…”

mentioning

confidence: 99%

A human intermediate conductance calcium-activated potassium channel

Ishii

Silvia

Hirschberg

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

554

491

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An intermediate conductance calciumactivated potassium channel, hIK1, was cloned from human pancreas. The predicted amino acid sequence is related to, but distinct from, the small conductance calcium-activated potassium channel subfamily, which is Ϸ50% conserved. hIK1 mRNA was detected in peripheral tissues but not in brain. Expression of hIK1 in Xenopus oocytes gave rise to inwardly rectifying potassium currents, which were activated by submicromolar concentrations of intracellular calcium (K 0.5 ‫؍‬ 0.3 M). Although the K 0.5 for calcium was similar to that of small conductance calcium-activated potassium channels, the slope factor derived from the Hill equation was significantly reduced (1.7 vs. 3.5). Single-channel current amplitudes ref lected the macroscopic inward rectification and revealed a conductance level of 39 pS in the inward direction. hIK1 currents were reversibly blocked by charybdotoxin (K i ‫؍‬ 2.5 nM) and clotrimazole (K i ‫؍‬ 24.8 nM) but were minimally affected by apamin (100 nM), iberiotoxin (50 nM), or ketoconazole (10 M). These biophysical and pharmacological properties are consistent with native intermediate conductance calcium-activated potassium channels, including the erythrocyte Gardos channel.

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Contribution of calcium‐activated potassium channels to the vasodilator effect of bradykinin in the isolated, perfused kidney of the rat

Cited by 34 publications

References 14 publications

Signal transduction pathways involved in kinin B₂ receptor‐mediated vasodilation in the rat isolated perfused kidney

Signal transduction pathways involved in kinin B₂ receptor‐mediated vasodilation in the rat isolated perfused kidney

ATP-dependent Activation of the Intermediate Conductance, Ca2+-activated K+ Channel, hIK1, Is Conferred by a C-terminal Domain

A human intermediate conductance calcium-activated potassium channel

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Contribution of calcium‐activated potassium channels to the vasodilator effect of bradykinin in the isolated, perfused kidney of the rat

Cited by 34 publications

References 14 publications

Signal transduction pathways involved in kinin B2 receptor‐mediated vasodilation in the rat isolated perfused kidney

Signal transduction pathways involved in kinin B2 receptor‐mediated vasodilation in the rat isolated perfused kidney

ATP-dependent Activation of the Intermediate Conductance, Ca2+-activated K+ Channel, hIK1, Is Conferred by a C-terminal Domain

A human intermediate conductance calcium-activated potassium channel

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Product

Resources

About

Signal transduction pathways involved in kinin B₂ receptor‐mediated vasodilation in the rat isolated perfused kidney

Signal transduction pathways involved in kinin B₂ receptor‐mediated vasodilation in the rat isolated perfused kidney