Lactate dilates cochlear capillaries via type V fibrocyte-vessel coupling signaled by nNOS

Min Dai, Yue Yang, Xiao Shi

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Transduction of sound in the inner ear demands tight control over delivery of oxygen and glucose. However, the mechanisms underlying the control of regional blood flow are not yet fully understood. In this study, we report a novel local control mechanism that regulates cochlear blood flow to the stria vascularis, a high energy-consuming region of the inner ear. We found that extracellular lactate had a vasodilatory effect on the capillaries of the spiral ligament under both in vitro and in vivo conditions. The lactate, acting through monocarboxylate transporter 1 (MCT1), initiated neuronal nitric oxide (NO) synthase (nNOS) and catalyzed production of NO for the vasodilation. Blocking MCT1 with the MCT blocker, α-cyano-4-hydroxycinnamate (CHC), or a suppressing NO production with either the nonspecific inhibitor of NO synthase, N G-nitro-L-arginine methyl ester (L-NAME), or either of two selective nNOS inhibitors, 3-bromo-7-nitroindazole or (4S)-N-(4- amino-5[aminoethyl]aminopentyl)-N'-nitroguanidine (TFA), totally abolished the lactate-induced vasodilation. Pretreatment with the selective endothelial NO synthase inhibitor, L-N 5-(1-iminoethyl)ornithine (L-NIO), eliminated the inhibition of lactate-induced vessel dilation. With immunohistochemical labeling, we found the expression of MCT1 and nNOS in capillary-coupled type V fibrocytes. The data suggest that type V fibrocytes are the source of the lactateinduced NO. Cochlear microvessel tone, regulated by lactate, is mediated by an NO-signaled coupling of fibrocytes and capillaries.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume301
Issue number4
DOIs
StatePublished - Oct 2011

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Nitric Oxide Synthase Type I
Cochlea
Nitric Oxide Synthase
Lactic Acid
Nitric Oxide
NG-Nitroarginine Methyl Ester
Inner Ear
Vasodilation
Spiral Ligament of Cochlea
Stria Vascularis
Ornithine
Nitric Oxide Synthase Type III
Regional Blood Flow
Microvessels
Dilatation
Oxygen
Glucose

Keywords

  • Cochlear capillary
  • Monocarboxylate transporter 1
  • Neuronal nitric oxide synthase

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)
  • Cardiology and Cardiovascular Medicine

Cite this

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title = "Lactate dilates cochlear capillaries via type V fibrocyte-vessel coupling signaled by nNOS",
abstract = "Transduction of sound in the inner ear demands tight control over delivery of oxygen and glucose. However, the mechanisms underlying the control of regional blood flow are not yet fully understood. In this study, we report a novel local control mechanism that regulates cochlear blood flow to the stria vascularis, a high energy-consuming region of the inner ear. We found that extracellular lactate had a vasodilatory effect on the capillaries of the spiral ligament under both in vitro and in vivo conditions. The lactate, acting through monocarboxylate transporter 1 (MCT1), initiated neuronal nitric oxide (NO) synthase (nNOS) and catalyzed production of NO for the vasodilation. Blocking MCT1 with the MCT blocker, α-cyano-4-hydroxycinnamate (CHC), or a suppressing NO production with either the nonspecific inhibitor of NO synthase, N G-nitro-L-arginine methyl ester (L-NAME), or either of two selective nNOS inhibitors, 3-bromo-7-nitroindazole or (4S)-N-(4- amino-5[aminoethyl]aminopentyl)-N'-nitroguanidine (TFA), totally abolished the lactate-induced vasodilation. Pretreatment with the selective endothelial NO synthase inhibitor, L-N 5-(1-iminoethyl)ornithine (L-NIO), eliminated the inhibition of lactate-induced vessel dilation. With immunohistochemical labeling, we found the expression of MCT1 and nNOS in capillary-coupled type V fibrocytes. The data suggest that type V fibrocytes are the source of the lactateinduced NO. Cochlear microvessel tone, regulated by lactate, is mediated by an NO-signaled coupling of fibrocytes and capillaries.",
keywords = "Cochlear capillary, Monocarboxylate transporter 1, Neuronal nitric oxide synthase",
author = "Min Dai and Yue Yang and Xiao Shi",
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T1 - Lactate dilates cochlear capillaries via type V fibrocyte-vessel coupling signaled by nNOS

AU - Dai, Min

AU - Yang, Yue

AU - Shi, Xiao

PY - 2011/10

Y1 - 2011/10

N2 - Transduction of sound in the inner ear demands tight control over delivery of oxygen and glucose. However, the mechanisms underlying the control of regional blood flow are not yet fully understood. In this study, we report a novel local control mechanism that regulates cochlear blood flow to the stria vascularis, a high energy-consuming region of the inner ear. We found that extracellular lactate had a vasodilatory effect on the capillaries of the spiral ligament under both in vitro and in vivo conditions. The lactate, acting through monocarboxylate transporter 1 (MCT1), initiated neuronal nitric oxide (NO) synthase (nNOS) and catalyzed production of NO for the vasodilation. Blocking MCT1 with the MCT blocker, α-cyano-4-hydroxycinnamate (CHC), or a suppressing NO production with either the nonspecific inhibitor of NO synthase, N G-nitro-L-arginine methyl ester (L-NAME), or either of two selective nNOS inhibitors, 3-bromo-7-nitroindazole or (4S)-N-(4- amino-5[aminoethyl]aminopentyl)-N'-nitroguanidine (TFA), totally abolished the lactate-induced vasodilation. Pretreatment with the selective endothelial NO synthase inhibitor, L-N 5-(1-iminoethyl)ornithine (L-NIO), eliminated the inhibition of lactate-induced vessel dilation. With immunohistochemical labeling, we found the expression of MCT1 and nNOS in capillary-coupled type V fibrocytes. The data suggest that type V fibrocytes are the source of the lactateinduced NO. Cochlear microvessel tone, regulated by lactate, is mediated by an NO-signaled coupling of fibrocytes and capillaries.

AB - Transduction of sound in the inner ear demands tight control over delivery of oxygen and glucose. However, the mechanisms underlying the control of regional blood flow are not yet fully understood. In this study, we report a novel local control mechanism that regulates cochlear blood flow to the stria vascularis, a high energy-consuming region of the inner ear. We found that extracellular lactate had a vasodilatory effect on the capillaries of the spiral ligament under both in vitro and in vivo conditions. The lactate, acting through monocarboxylate transporter 1 (MCT1), initiated neuronal nitric oxide (NO) synthase (nNOS) and catalyzed production of NO for the vasodilation. Blocking MCT1 with the MCT blocker, α-cyano-4-hydroxycinnamate (CHC), or a suppressing NO production with either the nonspecific inhibitor of NO synthase, N G-nitro-L-arginine methyl ester (L-NAME), or either of two selective nNOS inhibitors, 3-bromo-7-nitroindazole or (4S)-N-(4- amino-5[aminoethyl]aminopentyl)-N'-nitroguanidine (TFA), totally abolished the lactate-induced vasodilation. Pretreatment with the selective endothelial NO synthase inhibitor, L-N 5-(1-iminoethyl)ornithine (L-NIO), eliminated the inhibition of lactate-induced vessel dilation. With immunohistochemical labeling, we found the expression of MCT1 and nNOS in capillary-coupled type V fibrocytes. The data suggest that type V fibrocytes are the source of the lactateinduced NO. Cochlear microvessel tone, regulated by lactate, is mediated by an NO-signaled coupling of fibrocytes and capillaries.

KW - Cochlear capillary

KW - Monocarboxylate transporter 1

KW - Neuronal nitric oxide synthase

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

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