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Biomedical subjects

F Schimek

Publications and source records attributed to F Schimek.

25 records · Page 2Linked to original sources
PubMed1984

New aspects of acid-base balance influences of NH4Cl on intra- and extracellular acid-base equilibrium studies in the rat.

Though buffers are widely used in daily practice, there is little information about their effect on intracellular pH in vivo. In this study, the effects of NH4Cl on intra- and extracellular acid-base equilibria were examined. Intact male Sprague-Dawley rats were infused with 3 mmol NH4Cl per kg body weight. Arterial plasma pH and pCO2 were measured at intervals for six hours. In addition, the "mean whole body (intracellular) pHi", an overall estimate of the intracellular pH (complementary to the in vivo determined arterial plasma pH) was calculated from the distribution of 14C labeled DMO (5,5-dimethyl-2,4-oxazolidinedione). For evaluation of buffering, extra- and intracellular bicarbonate was calculated from the Henderson-Hasselbalch equation. Though a decrease of pHe (extracellular pH) by 0.12 pH units was found just after infusion of NH4Cl, pHi increased over the 6 hours of investigation by 0.08 pH units. Extracellular bicarbonate was reduced but there was little change in intracellular bicarbonate concentration. For the treatment of metabolic alkalosis, therapeutic agents are given to reduce intracellular pH and intracellular bicarbonate concentration.. However, it was found in this study that NH4Cl has no effect on intracellular bicarbonate concentration. In addition, infusion of NH4Cl causes an increase of intracellular pH which cannot be detected by blood-gas measurements. The intracellular pH increase that we have demonstrated may have adverse consequences for patients and raises objections to the use of NH4Cl in the treatment of metabolic alkalosis.

Acid-Base Equilibrium↗
PubMed1984

Differential effects of glucose and potassium lack in conduction block of myelinated and unmyelinated axons.

The effect of potassium on conduction in myelinated and unmyelinated axons lacking glucose was investigated in vitro. In the presence of ambient potassium neural excitability was lost after the same period of time in both myelinated and unmyelinated fibers. In the absence of potassium in the incubation solution however, the extinction times of the unmyelinated axons only (p less than 0.01), but not those of the myelinated ones were delayed. It is suggested that unmyelinated C fibers are more energy efficient than myelinated A axons.

Action Potentials↗
PubMed1983

Effects of nitrous oxide, transcutaneous electrical stimulation, and their combination on brain potentials elicited by painful stimulation.

Combinations of transcutaneous electrical stimulation (TES) and inhalation of nitrous oxide with oxygen have been used for surgical pain control and this report explored the possible synergism of these two treatments. During painful dental stimulation, 18 subjects gave pain reports while event-related potentials were recorded at vertex. Electrical stimulation was delivered bilaterally at the LI-4 acupuncture points on the hands at 20 Hz, mean = 9.65 mA intensity. Inhalation treatment was nitrous oxide 33% with oxygen. Testing was done on two days to permit evaluation of each treatment alone and their combination. Treatment sequence was counterbalanced. Base-to-peak amplitude and peak latency scores were derived for the event-related potentials under each testing condition. Both stimulation and inhalation treatments altered event-related potential scores and pain report. The combination treatment was significantly more effective than stimulation alone but was not significantly more effective than nitrous oxide alone. Nitrous oxide with oxygen alone reduced peak amplitude at 250 ms and 350 ms, as well as pain report. It increased peak latency at 100 ms. Transcutaneous electrical stimulation alone decreased peak amplitude and latency at 150 ms and increased peak latency at 350 ms. Decreased peak amplitude at 250 ms and increased peak latency at 150 ms were observed when inhalation was added to stimulation, and there was also a significant reduction in pain report. Nine control subjects were studied to demonstrate that analgesic changes were not due to repeated testing. These outcomes demonstrated no synergism between the stimulation and inhalation treatments. The data suggest that nitrous oxide blocks the effects of electrical stimulation at LI-4.

Adult↗
PubMed1983

[Paradoxical reaction of intracellular pH values during therapy of acid-base imbalance with arginine hydrochloride].

A well known complication following surgical intervention is metabolic alkalosis. In general this acid-base disturbance is treated in our intensive care units by application of arginine-hydrochloride. In an experimental study on rats in vivo we determined the influence of this substance on the acid-base status of the extra- and intracellular body compartment. It was found that the extracellular bicarbonate decreases but there is nearly no influence on intracellular buffering. The "mean whole body pHi", an overall estimate of the intracellular pH as complementary to the in vivo determined extracellular plasma pH, was determined with DMO (5,5-dimethyl-2,4-oxazolidinedione) and shown to increase significantly after application of arginine-HCl. From this result it is concluded that arginine-hydrochloride should no longer be used for clinical therapy of metabolic alkalosis.

Acid-Base Equilibrium↗
PubMed1982

Varying electrical acupuncture stimulation intensity: effects on dental pain-evoked potentials.

Electrical acupunctural stimulation (EAS) has repeatedly been shown in the laboratory to diminish human dental pain perception. This study compared the effects of low, medium, and high EAS levels on event-related potentials elicited by painful dental stimulation and on subjective pain report. Acupuncture was performed bilaterally at LI-4 on the hands, and each subject received all EAS levels, counterbalanced for order. Only the highest level of EAS was effective, and it reduced the pain report in addition to the amplitudes of the positive event-related potential deflections from base line at 100 and 250 msec. No dose-response effect was observed for EAS levels. The outcome suggests that the analgesic effect occurs abruptly when stimulation reaches a strong level and a subnoxious pounding sensation is elicited.

Acupuncture Therapy↗
PubMedDate not supplied

Stereotactic retrobulbar anesthesia using CT.

A simple technique using stereotactic needle placement for retrobulbar anesthesia is reported. The method utilizes a CT-guided stereotactic device that permits precise intraconal injection of local anesthetics; in addition, the risk of injury to muscles, vessels, eyeglobe, or optic nerve is substantially reduced.

Anesthesia, Local↗