Cerebral intracellular pH regulation during hypercapnia in unanesthetized rats: a 31P nuclear magnetic resonance spectroscopy study
| Autor: | Josiane Borredon, Bertrand Barrere, Jean-Claude Beloeil, Guy Berenger, P. Meric, Jacques Seylaz |
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| Rok vydání: | 1990 |
| Předmět: |
Male
medicine.medical_specialty Intracellular pH Phosphocreatine Hypercapnia chemistry.chemical_compound In vivo Internal medicine Parenchyma medicine Animals Molecular Biology General Neuroscience Brain Rats Inbred Strains Nuclear magnetic resonance spectroscopy Hydrogen-Ion Concentration Magnetic Resonance Imaging Rats Endocrinology Biochemistry chemistry Breathing Neurology (clinical) medicine.symptom Adenosine triphosphate Developmental Biology |
| Zdroj: | Brain research. 516(2) |
| ISSN: | 0006-8993 |
| Popis: | The energy metabolism and the brain intracellular pH regulation under arterial CO2 tensions of 25–90 mm Hg were investigated in unanesthetized spontaneously breathing rats by in vivo phosphorus nuclear magnetic resonance spectroscopy (31P NMR). The31P brain spectra, recorded with a high resolution spectrometer (AM 400 Brucker), allowed repeated non-invasive measurements of cerebral pH (pHi), phosphocreatine (PCr), inorganic phosphate (Pi) and adenosine triphosphate (ATP) levels in 15 rats breathing a gas mixture containing 21% O2, N2, and a varied percentage of CO2. The pHi decreased significantly when thepa CO2 was increased by hypercapnia. The percentage of pH regulation, estimated from the linear regression analysis of pHi versus the logarithm of thepa CO2 was 78%. This result indicates that spontaneously breathing unanesthetized animals have better pHi regulation under hypercapnia than do paralyzed mechanically-ventilated animals under anesthesia. It also indicates a higher pH regulation ability in the range of hypercapnia investigated than that estimated for higher levels of hypercapnia in previous studies on unanesthetized animals, suggesting that there is a threshold for this highly efficient regulation. Furthermore, there were no significant correlations between the PCr, ATP and Pi levels and thepa CO2 levels during hypercapnia. This indicates that physiological variations of the CO2 tension in the blood, and consequently in the brain parenchyma, have little effect on cerebral energy metabolism in unanesthetized spontaneously breathing animals. |
| Databáze: | OpenAIRE |
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