Rapid Communication: Response of the Human Brain to a Hypercapnic Acid Load in Vivo

1990 ◽  
Vol 79 (1) ◽  
pp. 1-3 ◽  
Author(s):  
T. A. D. Cadoux-Hudson ◽  
B. Rajagopalan ◽  
J. G. G. Ledingham ◽  
G. K. Radda
Keyword(s):  
White Matter ◽  
Human Brain ◽  
Intracellular Ph ◽  
Grey Matter ◽  
Resonance Spectroscopy ◽  
Rotating Frame ◽  
End Tidal ◽  
End Tidal Co2 ◽  
Deep Brain

1. The aim of this investigation was to measure the change in intracellular pH of human brain in vivo in response to hypercapnia. 2. Five healthy male subjects inspired air for 20 min and then 5% CO2/95% O2 for 30 min, of which the first 10 min was used to achieve a steady-state end-tidal CO2 measurement. 3. 31P nuclear magnetic resonance spectroscopy was used to measure intracellular pH while breathing air and during hypercapnia. Simultaneous localization between superficial and deep brain was achieved by using the phase-modulated rotating frame imaging technique. One subject volunteered to breath air for a further phase-modulated rotating frame imaging study while recovering from hypercapnia. 4. End-tidal CO2 increased when breathing 5% CO2/95% O2 (on air, 5.57 ± 0.21%; on 5% CO2/95% O2, 6.41 ± 0.16%; rise = +0.84 ± 0.09%; means ± sem) causing a reduction in brain intracellular pH, which was more pronounced in deep brain (5 cm = mainly white matter, from 7.02 ± 0.006 pH units to 6.96 ± 0.001 pH units, mean ± sem) than in superficial brain (2 cm = mainly grey matter, from 7.02 ± 0.006 pH units to 7.00 ± 0.006 pH units, mean ± sem). 5. The white matter responded to hypercapnia with a greater fall in intracellular pH than the grey matter. This could either be due to differences in blood flow between grey and white matter in response to hypercapnia or to differences in intracellular pH regulation/buffering between these two tissues.

Increase of total creatine in human brain after oral supplementation of creatine-monohydrate

1999 ◽  
Vol 277 (3) ◽  
pp. R698-R704 ◽  
Author(s):  
P. Dechent ◽  
P. J. W. Pouwels ◽  
B. Wilken ◽  
F. Hanefeld ◽  
J. Frahm
Keyword(s):  
White Matter ◽  
Human Brain ◽  
Gray Matter ◽  
Regional Analysis ◽  
Creatine Supplementation ◽  
Brain Regions ◽  
Creatine Monohydrate ◽  
Resonance Spectroscopy ◽  
Total Creatine

The effect of oral creatine supplementation on brain metabolite concentrations was investigated in gray matter, white matter, cerebellum, and thalamus of healthy young volunteers by means of quantitative localized proton magnetic resonance spectroscopy in vivo (2.0 T, stimulated echo acquisition mode sequence; repetition time = 6,000 ms, echo time = 20 ms, middle interval = 10 ms, automated spectral evaluation). Oral consumption of 4 × 5 g creatine-monohydrate/day for 4 wk yielded a statistically significant increase (8.7% corresponding to 0.6 mM, P < 0.001) of the mean concentration of total creatine (tCr) when averaged across brain regions and subjects ( n = 6). The data revealed considerable intersubject variability (3.5–13.3%), with the smallest increases observed for the two male volunteers with the largest body weights. A regional analysis resulted in significant increases of tCr in gray matter (4.7%), white matter (11.5%), and cerebellum (5.4%) and was most pronounced in thalamus (14.6% corresponding to 1.0 mM). Other findings were significant decreases of N-acetyl-containing compounds in cerebellum and thalamus as well as of choline-containing compounds in thalamus. All cerebral metabolic alterations caused by oral Cr were reversible, as evidenced by control measurements at least 3 mo after the diet. This work demonstrates that excess consumption of Cr yields regionally dependent increases of the tCr concentration in human brain over periods of several weeks.

scholarly journals Measurement of the Tricarboxylic Acid Cycle Rate in Human Grey and White Matter in Vivo by 1H-[13C] Magnetic Resonance Spectroscopy at 4.1T

1999 ◽  
Vol 19 (11) ◽  
pp. 1179-1188 ◽  
Author(s):  
Graeme F. Mason ◽  
Jullie W. Pan ◽  
Wen-Jan Chu ◽  
Bradley R. Newcomer ◽  
Yantian Zhang ◽  
...  
Keyword(s):  
White Matter ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Grey Matter ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Resonance Spectroscopy ◽  
Acid Cycle ◽  
Cycle Rate

13C isotopic labeling data were obtained by 1H-observed/13C-edited magnetic resonance spectroscopy in the human brain in vivo and analyzed using a mathematical model to determine metabolic rates in human grey matter and white matter. 22,5-cc and 56-cc voxels were examined for grey matter and white matter, respectively. When partial volume effects were ignored, the measured tricarboxylic acid cycle rate was 0.72 ± 0.22 (mean ± SD) and 0.29 ± 0.09 μmol min–1 g–1(mean ± SD) in voxels of ∼70% grey and ∼70% white matter, respectively. After correction for partial volume effects using a model with two tissue compartments, the tricarboxylic acid cycle rate in pure grey matter was higher (0.80 ± 0.10 mol min–1 g–1; mean ± SD) and in white matter was significantly lower (0.17 ± 0.01 μmol min–1 g–1; mean ± SD). In 1H-observed/13C-edited magnetic resonance spectroscopy labeling studies, the larger concentrations of labeled metabolites and faster metabolic rates in grey matter biased the measurements heavily toward grey matter, with labeling time courses in 70% grey matter appearing nearly identical to labeling in pure grey matter.

4-Chloro-m-cresol Triggers Malignant Hyperthermia in Susceptible Swine at Doses Greatly Exceeding Those Found in Drug Preparations

1999 ◽  
Vol 90 (6) ◽  
pp. 1723-1732. ◽  
Author(s):  
Paul A. Iaizzo ◽  
Brooks A. Johnson ◽  
Kaoru Nagao ◽  
William J. Gallagher
Keyword(s):  
Malignant Hyperthermia ◽  
Blood Chemistry ◽  
Response Curves ◽  
End Tidal ◽  
In Vivo Effects ◽  
Higher Doses ◽  
End Tidal Co2 ◽  
Cardiovascular Reactions

Background Chlorocresols are used as preservatives in numerous commercial drugs that have been shown to induce myoplasmic Ca2+ release; the most potent isoform is 4-chloro-m-cresol. The aims of this study were to (1) examine the in vivo effects of 4-chloro-m-cresol on swine susceptible to malignant hyperthermia and (2) contrast in vivo versus in vitro dose-response curves. Methods Susceptible swine (weight: 38.5 kg+/-3.55 kg) were anesthetized and monitored for variations in physiological responses, including end-tidal CO2, heart rate, blood pressure, blood chemistry, and temperatures. In the first animals studied, 4-chloro-m-cresol, at equivalent cumulative doses of 0.14, 0.28, 0.57, 1.14, 2.27, 4.54, and 9.08 mg/kg (n = 3; 12.5, 25, 50, 100, 200, 400, and 800 micromol) were administered, and in a second group, larger doses were used: 1.14, 3.41, 7.95, 17.04 (n = 4), and/or 35.22 (n = 1) mg/kg (100, 300, 700, 1,500, and/or 3,100 micromol). For comparison, in vitro rectus abdominis muscle preparations obtained from normal and susceptible swine were exposed to 4-chloro-m-cresol, at cumulative concentrations of 6.25, 12.5, 25, 50, 100, 200, 400, 800, and 1,600 micromol; standard caffeine and halothane contracture testing was also performed. Results Episodes of malignant hyperthermia were not triggered in response to administration of low doses of 4-chloro-m-cresol, but transient cardiovascular reactions (e.g., tachycardia, arrhythmias, and hypotension) were observed. Subsequently, episodes in these animals were triggered when halothane (0.87; 1 MAC) and succinylcholine (2 mg/kg) were given. Animals administered the higher doses of 4-chloro-m-cresol all had fulminant episodes of malignant hyperthermia that were fatal, when equivalent cumulative concentrations were greater than 1,500 micromol. The levels of 4-chloro-m-cresol in the plasma rapidly decreased: e.g., 5 min postadministration of the 1,500-micromol dose, the mean plasma level was only 52+/-18 micromol (n = 4). Hemolysis was detected following 4-chloro-m-cresol administration at concentrations &gt; 200 micromol. In vitro, muscle from susceptible animals elicited contractures &gt; 200 mg at 50-micromol bath concentrations of 4-chloro-m-cresol (n = 29), whereas normal muscle did not elicit such contractures until bath concentrations were &gt; 800 micromol (n = 10). Conclusions 4-chloro-m-cresol is a trigger of malignant hyperthermia in susceptible swine, but only when serum concentrations are far above those likely to be encountered in humans. A relatively low concentration of 4-chloro-m-cresol, 50 micromol, is sufficient to activate sarcoplasmic [Ca+2] release in vitro (e.g., contractures); this same bolus dose administered in vivo (0.57 mg/kg) has minimal effects due to the rapid decrease in its plasma levels.

scholarly journals Metabolic Maturation of the Human Brain From Birth Through Adolescence: Insights From In Vivo Magnetic Resonance Spectroscopy

2012 ◽  
Vol 23 (12) ◽  
pp. 2944-2955 ◽  
Author(s):  
S. Bluml ◽  
J. L. Wisnowski ◽  
M. D. Nelson ◽  
L. Paquette ◽  
F. H. Gilles ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Human Brain ◽  
Resonance Spectroscopy

Diaphragmatic fatigue assessed by 31P-magnetic resonance spectroscopy in vivo

1993 ◽  
Vol 264 (5) ◽  
pp. C1111-C1118 ◽  
Author(s):  
D. G. Nichols ◽  
J. R. Buck ◽  
S. M. Eleff ◽  
D. C. Shungu ◽  
J. L. Robotham ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Intracellular Ph ◽  
Oxidative Metabolism ◽  
Compound Action Potential ◽  
Separate Group ◽  
Resonance Spectroscopy ◽  
Transdiaphragmatic Pressure ◽  
Control Value

We tested whether fatigue of the piglet diaphragm is associated with inadequate oxidative metabolism as measured by magnetic resonance spectroscopy (MRS). An MRS measured ratio of inorganic phosphate to phosphocreatine (Pi/PCr) > or = 1 was taken as evidence of inadequate oxidative metabolism. Piglets (n = 10) underwent phrenic nerve pacing for 90 min with stimulation frequency of 30 Hz and duty cycle of 0.33. In a separate group of six piglets PCr, Pi, ATP, and intracellular pH were measured by in vivo MRS, and diaphragmatic blood flow was measured with radioactive microspheres at control, 2, 10, 45, 60, and 90 min of pacing. Transdiaphragmatic pressure fell from 25 +/- 3 to 15 +/- 2 mmHg (61 +/- 5%) at 2 min and remained depressed in a separate group of four piglets (P < 0.05). Conversely, compound action potential amplitude remained constant for the first 10 min of pacing and fell to 68 +/- 5% of control at 45 min (P < 0.05). Pi/PCr rose from a control value of 0.32 +/- 0.06 to 0.92 +/- 0.23 at 2 min and 0.79 +/- 0.03 at 10 min (P < 0.05) before returning toward control at 45-90 min. O2 delivery increased from 4.6 +/- 1.2 to 24.7 +/- 4.8 ml.min-1.100 g-1 at 2 min and 18.4 +/- 2.2 ml.min-1.100 g-1 at 10 min (P < 0.05) but then fell to lower levels at 45-90 min. ATP and intracellular pH remained constant except for a decline in pH to 6.98 +/- 0.09 at 45 min (P < 0.05) from the control value of 7.26 +/- 0.06.(ABSTRACT TRUNCATED AT 250 WORDS)

Sign in / Sign up

Export Citation Format

Share Document