Intracellular pH response to hypercapnia in neurons from chemosensitive areas of the medulla
| Autor: | Robert W. Putnam, Nick A. Ritucci, Jay B. Dean |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
Hypoglossal Nerve
medicine.medical_specialty Time Factors Chemoreceptor Physiology Intracellular pH Central nervous system 4 4'-Diisothiocyanostilbene-2 2'-Disulfonic Acid In Vitro Techniques Olivary Nucleus Biology Ammonium Chloride Amiloride Rats Sprague-Dawley Physiology (medical) Internal medicine Solitary Nucleus medicine Animals Homeostasis Medulla Fluorescent Dyes Neurons Medulla Oblongata Solitary tract Anatomy Carbon Dioxide Hydrogen-Ion Concentration Fluoresceins Rats Kinetics Endocrinology medicine.anatomical_structure nervous system Medulla oblongata medicine.symptom Hypercapnia Nucleus |
| Zdroj: | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 273:R433-R441 |
| ISSN: | 1522-1490 0363-6119 |
| DOI: | 10.1152/ajpregu.1997.273.1.r433 |
| Popis: | We investigated whether neurons in two chemosensitive areas of the medulla oblongata [nucleus of the solitary tract (NTS) and ventrolateral medulla (VLM)] respond to hypercapnia differently than neurons in two nonchemosensitive areas of the medulla oblongata [inferior olive (IO) and hypoglossal nucleus (Hyp)]. Medullary brain slices from preweanling Sprague-Dawley rats were loaded with 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein, and intracellular pH (pHi) was followed in individual neurons at 37 degrees C with the use of a fluorescence imaging system. Most neurons from the NTS and VLM did not exhibit pHi recovery when CO2 was increased from 5 to 10% at constant extracellular HCO3- concentration [extracellular pH (pHo) decreased approximately 0.3 pH unit] (hypercapnic acidosis). However, when CO2 was increased from 5 to 10% at constant pHo (isohydric hypercapnia), pHi recovery was seen. In contrast, all neurons from the IO and Hyp exhibited pHi recovery during hypercapnic acidosis. All pHi recovery in the four areas studied was inhibited by 1 mM amiloride and unaffected by 0.5 mM 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid. These data indicate that 1) pHi regulation differs between neurons in chemosensitive (NTS and VLM) and nonchemosensitive (IO and Hyp) areas of the medulla, 2) pHi recovery is due solely to Na+/H+ exchange in all four areas, and 3) Na+/H+ exchange is more sensitive to inhibition by extracellular acidosis in NTS and VLM neurons than in IO and Hyp neurons. |
| Databáze: | OpenAIRE |
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