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B E Hetzler

Publications and source records attributed to B E Hetzler.

12 recordsLinked to original sources
PubMed1989

Effects of ketamine, naloxone, and physostigmine on flash evoked potentials in rat superior colliculus.

Flash evoked potentials were recorded from the superior colliculus of chronically implanted hooded rats at 5 and 20 min following IP injections of saline, ketamine (75 mg/kg), naloxone (10 mg/kg), or physostigmine (0.4 mg/kg) on separate days. Components in an early positive complex were unaffected by ketamine and naloxone, but were reduced in amplitude by physostigmine. A positive spike emerged from the middle of a later negative wave following ketamine administration, but the amplitude of the negative wave was unaltered by naloxone or physostigmine. A succeeding positive component was enhanced by both ketamine and physostigmine. Physostigmine produced the most consistent alterations in latency, with most components increasing in latency. Naloxone pretreatment did not alter ketamine's influence on evoked potential amplitudes. Pretreatment with physostigmine briefly decreased the amplitude of the ketamine-induced positive spike, augmented the amplitude of the succeeding positive component, and also increased most peak latencies. Ketamine, naloxone and physostigmine all produced approximately equivalent hypothermia. Physostigmine, but not naloxone, pretreatment augmented the ketamine-induced hypothermia. The body temperature data suggest that some of the observed latency alterations are secondary to hypothermia. The amplitude data indicate that ketamine and physostigmine produce a combination of similar, distinct, and antagonistic effects on evoked potentials.

Animals↗
PubMed1988

Temperature-dependent changes in visual evoked potentials of rats.

The effects of alterations in body temperature on flash and pattern reversal evoked potentials (FEPs and PREPs) were examined in hooded rats whose thermoregulatory capacity was compromised with lesions of the preoptic/anterior hypothalamic area and/or cold restraint. Body temperature, measured with a rectal thermometer, was manipulated via exposure to different ambient temperatures. To describe the data, a model was used in which both linear and quadratic relationships could be estimated. PREP amplitudes were not significantly influenced by body temperature over the range of 27-42 degrees C, although in one experiment FEP amplitudes did show a linear decline as temperatures fell below approximately 30 degrees C. Both FEP and PREP latencies were strongly influenced by temperature and became progressively longer as body temperature was lowered. The non-linear component affecting latencies became more prominent as body temperature decreased. These data demonstrate the temperature dependence of FEP and PREP latencies independent of anesthetic or other drugs.

Animals↗
PubMed1987

Differential effects of ethanol on photic and acoustic evoked potentials in the reticular formation of rats.

Flash and click evoked potentials were recorded from the same electrode in the midbrain reticular formation of hooded rats. Animals were given i.p. injections of saline, 0.25, 0.5, 1.0 or 2.0 g ethanol/kg body wt. on separate days. The click data demonstrated both a biphasic effect of ethanol and an enhanced sensitivity relative to the flash data. It is suggested that differing evoking stimuli may sample the activity of functionally different populations of neurons within the reticular formation.

Animals↗
PubMed1985

Ketamine-induced locomotion in rats in an open-field.

The effects of ketamine on locomotion in an open-field were determined in hooded rats. Animals were given intraperitoneal injections of saline, or of 1, 10, 50 or 100 mg ketamine/kg body weight on separate days. Open-field behavior was examined for 60 min following injection. The 50 mg/kg dose of ketamine produced an increase in locomotion which peaked approximately 30 min after injection. A cataleptic immobility produced by the 100 mg/kg dose was followed by postanesthetic locomotion. The ketamine-induced locomotion consisted largely of ambulation about the perimeter of the field and was accompanied by ataxia, but included relatively little tight circling (rotation) during the peak of activity. Comparisons with the results of past research suggests that test-chamber design influences the type of locomotion induced by ketamine.

Animals↗
PubMed1973

Operant-controlled evoked responses: discrimination of conditioned and normally occurring components.

Rats were rewarded for signaling large and small sensory evoked components with appropriate bar presses. Most rats operantly generated large components and correctly signaled only these. Two rats correctly signaled successful and unsuccessful attempts to generate large waves. One rat discriminated component amplitudes without operantly attempting to generate specific wave types.

Animals↗
PubMedDate not supplied

Differential impact of hypothermia and pentobarbital on brain-stem auditory evoked responses.

Two experiments were conducted to determine the effects of hypothermia and pentobarbital anesthesia, alone and in combination, on the brain-stem auditory evoked responses (BAERs) of rats. In experiment I, unanesthetized rats were cooled to colonic temperatures 0.5 and 1.0 degrees C below normal. In experiment II, 2 groups of rats were cooled and tested at 37.5, 36.0, 34.5 and 31.5 degrees C. One group was anesthetized during testing and the other group was awake. The rat BAER was sensitive to cooling of 1 degree C or less. Peak latencies were prolonged and peak-to-peak amplitudes were increased by hypothermia alone. The effect on amplitude may be related to the time course of temperature change or to stimulus level. Pentobarbital significantly affected both latencies and amplitudes over and above the effects of cooling. The specific effects of pentobarbital differed by BAER peak and by temperature. The findings point up the importance of the potential confound of anesthetic drugs in most of the evoked potential literature on hypothermia and, for the first time, quantify the complex interactions between pentobarbital and temperature which affect the BAER wave form.

Anesthesia↗
PubMedDate not supplied

Acute sulfolane exposure produces temperature-independent and dependent changes in visual evoked potentials.

Sulfolane (tetrahydrothiophene-1, 1-dioxide) is a commercially important solvent. This report describes the consequences of acute exposure to sulfolane upon the visual system, as measured using flash evoked potentials (FEPs) and pattern reversal evoked potentials (PREPs). A single injection of either 1/2 or 1/4, but not 1/8 the IP LD50 (1600 mg/kg) produced significant changes in both FEPs and PREPs which were apparent within 1 hour and lasted longer than 6 hours. Amplitudes of FEP peaks to the first of a pair of stimuli were generally increased compared to control, an effect which was not temperature-dependent. In addition, sulfolane produced an ambient temperature- and dose-dependent hypothermia. Sulfolane increased latencies of FEP and PREP peaks, but attenuating hypothermia eliminated the effect of sulfolane on latencies.

Animals↗