Hypocapnia reduces the T wave of the electrocardiogram in normal human subjects

2005 ◽  
Vol 289 (1) ◽  
pp. R148-R155 ◽  
Author(s):  
J. J. Rutherford ◽  
T. H. Clutton-Brock ◽  
M. J. Parkes
Keyword(s):  
Healthy Subjects ◽  
Wave Amplitude ◽  
Human Subjects ◽  
Coronary Artery Spasm ◽  
Normal Subjects ◽  
T Wave ◽  
Diagnostic Potential ◽  
Normal Human ◽  
Electrocardiogram Ecg ◽  
Mean Heart Rate

During voluntary hyperventilation in unanesthetized humans, hypocapnia causes coronary vasoconstriction and decreased oxygen (O2) supply and availability to the heart. This can induce local epicardial coronary artery spasm in susceptible patients. Its diagnostic potential for detection of early heart disease is unclear. This is because such hypocapnia produces an inconsistent and irreproducible effect on electrocardiogram (ECG) in healthy subjects. To resolve this inconsistency, we have applied two new experimental techniques in normal, healthy subjects to measure the effects of hypocapnia on their ECG: mechanical hyperventilation and averaging of multiple ECG cycles. In 15 normal subjects, we show that hypocapnia (20 ± 1 mmHg) significantly reduced mean T wave amplitude by 0.1 ± 0.0 mV. Hypocapnia also increased mean heart rate by 4 beats/min without significantly altering blood pressure, ionized calcium or potassium levels, or the R wave or other features of the ECG. We therefore provide the first unequivocal demonstration that hypocapnia does consistently reduce T wave amplitude in normal, healthy subjects.

Electrical Activity from the Superior Pharyngeal Constrictor During Reflexive and Nonreflexive Tasks

1989 ◽  
Vol 32 (4) ◽  
pp. 749-754 ◽  
Author(s):  
Adrienne L. Perlman ◽  
Erich S. Luschei ◽  
Charles E. Du Mond
Keyword(s):  
Electrical Activity ◽  
Healthy Subjects ◽  
General Trend ◽  
Human Subjects ◽  
Electrode Placement ◽  
Emg Activity ◽  
Constrictor Muscle ◽  
Natural Logarithm ◽  
Quantitative Manner ◽  
Normal Human

The purpose of this investigation was to determine, in a quantitative manner, which, if any, nonswallowing tasks produce significant levels of activation in the superior pharyngeal constrictor muscle of normal human subjects. Bipolar hooked wire electrodes were inserted in the superior pharyngeal constrictor muscle of 15 healthy subjects. Electrode placement was controlled. Each subject performed two reflexive tasks, six voluntary tasks requiring phonation, and four nonspeech voluntary tasks. The electromyogram (EMG) was rectified and integrated. The resulting number was then transformed by taking its natural logarithm. An ANOVA was performed and a linear model was estimated. The magnitude of the EMG activity was related to the location of the electrodes. The largest values were recorded in the lateral-superior placement, followed by the lateral-inferior, medial-inferior and medial-superior. The superior pharyngeal contrictor was found to be a muscle activated primarily during reflexive activity. There was a general trend in the amplitude of EMG activity in relationship to task. Swallowing produced the greatest amount of activity and a gag produced about 60% of the activity produced by the swallow. Two tasks, production of the work /hk/ in which the phoneme /k/ was stressed, and a "modified Valsalva," which was actually a hard /k/ held for several seconds, produced the next greatest level of EMG.

Platelet catecholamines and platelet function in normal human subjects

1987 ◽  
Vol 73 (1) ◽  
pp. 99-103 ◽  
Author(s):  
A. P. Wilson ◽  
C. C. T. Smith ◽  
B. N. C. Prichard ◽  
D. J. Betteridge
Keyword(s):  
Platelet Function ◽  
High Performance ◽  
Human Subjects ◽  
Normal Subjects ◽  
Noradrenaline Content ◽  
Collagen Concentration ◽  
Normal Human ◽  
Wall Interaction ◽  
Local Release

1. We have used high-performance liquid chromatography with electrochemical detection to measure plasma and platelet catecholamines in 24 normal subjects. 2. In the same subjects platelet function was assessed by measuring platelet aggregation in response to adenosine 5′-pyrophosphate, thrombin, adrenaline and collagen. Platelet sensitivity to prostacyclin was also examined. 3. Platelet noradrenaline showed a positive correlation with extent of aggregation induced by ‘low-dose’ collagen (1 μg/ml). No correlation was seen at the higher collagen concentration. 4. Platelet noradrenaline content also correlated with sensitivity of platelets to prostacyclin. High platelet noradrenaline concentrations appeared to result in decreased sensitivity to prostacyclin. 5. No other correlations were observed. 6. These data suggest that platelet noradrenaline rather than plasma levels may be involved in modifying platelet function in vivo. Local release of platelet catecholamines may affect the platelet/vessel wall interaction, the primary physiological step in platelet activation.

Catechol O-Methyltransferase in Red Blood Cells of Schizophrenic, Depressed, and Normal Human Subjects

1976 ◽  
Vol 128 (2) ◽  
pp. 184-187 ◽  
Author(s):  
Helen L. White ◽  
Malcolm N. McLeod ◽  
Jonathan R. T. Davidson
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Human Subjects ◽  
Normal Subjects ◽  
Enzyme Preparations ◽  
Human Red Blood Cells ◽  
Schizophrenic Patients ◽  
Normal Human ◽  
The Mean ◽  
Isoelectric Ph

SummaryCatechol O-methyltransferase of lysed human red blood cells was assayed under optimal conditions, using saturating concentrations of the substrates, S-adenosyl-L-methionine and 3,4-dihydroxybenzoic acid. The mean enzyme activity found in 24 normal subjects was 29.2 nmol/hr/ml RBC. The mean activity in blood of 33 female unipolar depressives was not significantly different from normal. However, higher enzyme activities were observed in the blood of 11 schizophrenic patients (38.9 nmol/hr/ml RBC). Partially purified enzyme preparations from blood of normal and schizophrenic individuals were indistinguishable with respect to substrate specificities, isoelectric pH values, and ratios of the two O-methylated products. Therefore it is unlikely that any defect in O-methylation which may occur in schizophrenia can be attributed to a change in the intrinsic properties of erythrocyte catechol O-methyltransferase.

Lithium and erythrocyte membrane cation carrier studies in normal and manic depressive subjects

1977 ◽  
Vol 7 (2) ◽  
pp. 229-233 ◽  
Author(s):  
G. J. Naylor ◽  
A. Smith ◽  
L. J. Boardman ◽  
D. A. T. Dick ◽  
E. G. Dick ◽  
...  
Keyword(s):  
Erythrocyte Membrane ◽  
Human Subjects ◽  
Normal Subjects ◽  
Sodium Concentration ◽  
Manic Depressive Psychosis ◽  
Manic Depressive ◽  
Normal Human ◽  
Potassium Influx ◽  
Erythrocyte Sodium

synopsisChanges in the erythrocyte membrane cation carrier following lithium ingestion in normal human subjects were studied; ouabain sensitive potassium influx fell significantly during the lithium treated phase. Lithium was fed to rats and no change in erythrocyte Na-K ATPase was shown. These findings contrast with studies of lithium in manic depressive psychosis. The fluctuations in the erythrocyte membrane cation carrier were studied in 5 normal subjects over 12 weeks and the correlations between the parameters calculated. The erythrocyte sodium concentration correlated positively with the ouabain sensitive potassium influx. This too contrasts with findings in manic depressive psychosis.

Cerebral metabolism of isotopic glucose in chronic mental disease

1959 ◽  
Vol 14 (5) ◽  
pp. 849-854 ◽  
Author(s):  
William Sacks
Keyword(s):  
Mental Disease ◽  
Cerebral Metabolism ◽  
Human Subjects ◽  
Psychiatric Patients ◽  
Normal Subjects ◽  
Main Site ◽  
Significant Difference ◽  
Normal Human ◽  
Average Activity ◽  
Theoretical Considerations

A previous investigation of cerebral metabolism of isotopic glucose in normal human subjects was extended and similar studies performed upon chronic psychiatric patients. With variously labeled glucose-C14 as substrates, average activity-time curves and values for cumulative C14O2 resulting from cerebral oxidation of labeled glucose showed no significant variations between normal and psychotic subjects. A significant difference (P < 0.02) between the two groups did occur in comparing the fraction of brain CO2 derived from glucose. Calculations using individual glucose-U-C14 experiments gave averages of 56% for normal subjects and 36% for mental patients. These values agreed with those derived from composite curves of variously labeled glucose. That less brain CO2 was derived from glucose in psychotic subjects seemed to indicate a greater dilution of some carbohydrate intermediate(s) by protein and/or lipid intermediate(s); and, possibly, a decreased cerebral oxidation of carbohydrate. Theoretical considerations suggested that pyruvate and/or lactate might be the main site(s) of dilution. Submitted on January 28, 1959

Functional magnetic stimulation of expiratory muscles: a noninvasive and new method for restoring cough

1998 ◽  
Vol 84 (4) ◽  
pp. 1144-1150 ◽  
Author(s):  
Vernon W. H. Lin ◽  
Caleb Hsieh ◽  
Ian N. Hsiao ◽  
James Canfield
Keyword(s):  
Critical Care ◽  
Neurological Disorders ◽  
Magnetic Stimulation ◽  
Human Subjects ◽  
Normal Subjects ◽  
Stimulation Parameters ◽  
Normal Human ◽  
Lower Thoracic Spine ◽  
Expiratory Muscles ◽  
Stimulation Of

The purpose of this study was to assess the effectiveness of functional magnetic stimulation (FMS) for producing expiratory function in normal human subjects. Twelve able-bodied normal subjects were recruited for this study. FMS of the expiratory muscles was performed by using a magnetic stimulator and placing the magnetic coil along the lower thoracic spine. Results showed that peak expired pressure, volume, and flow rate generated by FMS at the end of normal inspiration (102.5 ± 13.62 cmH2O, 1.6 ± 0.16 liters, and 4.8 ± 0.35 l/s, respectively) were comparable to their voluntary maximal levels ( P > 0.1). The optimal coil placement was between T7 and T11, and the optimal stimulation parameters were a frequency of 25 Hz and 70–80% of maximal intensity. We conclude that 1) FMS of the lower thoracic nerves in normal subjects resulted in a significant expiratory function comparable to their voluntary maximum; 2) FMS was noninvasive and was well tolerated by all subjects; and 3) FMS may be useful to produce cough in patients in critical care or perioperative settings, or in patients with neurological disorders.

Perception of changes in breathing in normal human subjects

1981 ◽  
Vol 50 (1) ◽  
pp. 78-83 ◽  
Author(s):  
N. Wolkove ◽  
M. D. Altose ◽  
S. G. Kelsen ◽  
P. G. Kondapalli ◽  
N. S. Cherniack
Keyword(s):  
Tidal Volume ◽  
Control Volume ◽  
Human Subjects ◽  
Respiratory Muscles ◽  
Intrathoracic Pressure ◽  
Normal Subjects ◽  
Volume Changes ◽  
Elastic Load ◽  
Normal Human ◽  
Pressure Changes

Respiratory sensation was evaluated in normal subjects from their ability to quantitate changes in tidal volume. Subjects attempted to duplicate or double tidal volumes of different sizes while breathing freely or against a resistive or elastic load. When the mechanical conditions during control and test breaths were constant, tidal volume duplication was accomplished with an error of approximately 100 ml, regardless of the control volume. The error in doubling, however, increased progressively with increasing control tidal volume. There was a greater error in both volume duplication and doubling when the mechanical conditions between control and test breaths were changed. When test breaths against a load followed unloaded control breaths, tidal volume failed to double, but intrathoracic pressure changes twice exceeded control values. Conversely, when unloaded test breaths followed loaded control breaths, pressure changes underwent less than a twofold increase while tidal volume more than doubled. The results indicate that tidal volume changes are normally sensed with considerable accuracy and suggest that both tidal volume per se, as well as the forces generated by the respiratory muscles, are used in the estimation of tidal volume changes.

Triacylglycerol in the human erythrocyte: quantification and fatty acyl turnover in normal subjects and chronic alcoholics

1991 ◽  
Vol 80 (4) ◽  
pp. 313-318 ◽  
Author(s):  
Brice Lerique ◽  
Marguerite Gastaldi ◽  
Jean Boyer
Keyword(s):  
Human Erythrocyte ◽  
Specific Activity ◽  
Neutral Lipids ◽  
Human Subjects ◽  
Minor Component ◽  
Normal Subjects ◽  
Fatty Acyl ◽  
Active Metabolites ◽  
A Value ◽  
Normal Human

1. Triacylglycerol in erythrocytes from normal human subjects was estimated to average 2.7 ± 0.7 nmol/1010 cells, equivalent to 0.07% of total lipids or 0.3% of neutral lipids. 2. The specific activity of triacylglycerol labelling attained by incubating intact erythrocytes with [3H]oleic acid was 10 nmol/μmol, a value 20-fold higher than that of the highest labelled phospholipid, sphingomyelin; as isolated by ultracentrifugation over a density gradient, the youngest erythrocytes exhibited a labelling rate 10-fold higher than that of older cells. 3. The triacylglycerol content was not modified in erythrocytes from chronic alcoholics, whereas the mean rate of triacylglycerol labelling was 31% (P <0.05) higher than that of control subjects, and did not normalize 4 weeks after alcohol withdrawal. 4. These results indicate that triacylglycerol, although a quantitatively minor component, is one of the most active metabolites in the lipid matrix of the human erythrocyte membrane and appears to be implicated in the membrane response to antagonistic agents.

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