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American Journal of Veterinary Research Nov 2008To determine the type of atrial fibrillation induced by use of 2 pacing protocols during fentanyl and pentobarbital anesthesia before and after administration of... (Comparative Study)
Comparative Study
OBJECTIVE
To determine the type of atrial fibrillation induced by use of 2 pacing protocols during fentanyl and pentobarbital anesthesia before and after administration of atropine and to determine the organization of electrical activity in the left and right atria during atrial fibrillation in German Shepherd Dogs.
ANIMALS
7 German Shepherd Dogs.
PROCEDURES
Extrastimulus and pacedown protocols were performed before and after atropine administration. Monophasic action potential spectral entropy and mean dominant frequency were calculated during atrial fibrillation.
RESULTS
Atrial fibrillation occurred spontaneously in 6 of 7 dogs. All 7 dogs had atrial fibrillation induced. Sustained atrial fibrillation occurred in 13 of 25 (52%) episodes induced by the extrastimulus protocol and in 2 of 12 episodes of atrial fibrillation induced by pacedown. After atropine administration, sustained atrial fibrillation did not occur, and the duration of the nonsustained atrial fibrillation (6 episodes in 2 dogs of 1 to 26 seconds) was significantly shorter than before atropine administration (25 episodes in 7 dogs of 1 to 474 seconds). The left atrium (3.67 +/- 0.08) had lower spectral entropy than the right atrium (3.81 +/- 0.03), indicating more electrical organization in the left atrium. The mean dominant frequency was higher in the left atrium in 3 dogs.
CONCLUSIONS AND CLINICAL RELEVANCE
Atrial fibrillation developed spontaneously and was induced in German Shepherd Dogs under fentanyl and pentobarbital anesthesia. Electrical activity was more organized in the left atrium than in the right atrium as judged by use of spectral entropy.
Topics: Action Potentials; Anesthetics, Intravenous; Animals; Arrhythmias, Cardiac; Atrial Fibrillation; Atropine; Dog Diseases; Dogs; Electrocardiography; Fentanyl; Pentobarbital
PubMed: 18980425
DOI: 10.2460/ajvr.69.11.1434 -
Japanese Circulation Journal Sep 2000The use of mongrel dogs for experimental purposes was recently restricted and this report presents the experience of creating an aortic dissection model in swine. All...
The use of mongrel dogs for experimental purposes was recently restricted and this report presents the experience of creating an aortic dissection model in swine. All the swine in group 1 were anesthetized without pentobarbital and the descending aorta was side-clamped during the creation of the aortic dissection. The false lumen of the completed dissection was patent in the long term despite not having the anchoring suture that the previous canine model required to stabilize the opening of the entry tear. All the swine anesthetized with pentobarbital (ie, group 2) died of heart failure either during cross-clamping of the descending aorta or postoperative aortography. In conclusion, creation of a thoracic aortic dissection is possible in swine, but cross-clamping of the thoracic descending aorta and pentobarbital anesthesia should be avoided.
Topics: Aortic Dissection; Animals; Aorta, Thoracic; Aortic Aneurysm; Disease Models, Animal; Pentobarbital; Swine; Vascular Patency
PubMed: 10981865
DOI: 10.1253/jcj.64.736 -
Experimental and Clinical... Aug 2011Response rate can influence the behavioral effects of many drugs. Reinforcement magnitude may also influence drug effects. Further, reinforcement magnitude can influence...
Response rate can influence the behavioral effects of many drugs. Reinforcement magnitude may also influence drug effects. Further, reinforcement magnitude can influence rate-dependent effects. For example, in an earlier report, we showed that rate-dependent effects of two antidepressants depended on reinforcement magnitude. The ability of reinforcement magnitude to interact with rate-dependency has not been well characterized. It is not known whether our previous results are specific to antidepressants or generalize to other drug classes. Here, we further examine rate-magnitude interactions by studying effects of two stimulants (d-amphetamine [0.32-5.6 mg/kg] and cocaine [0.32-10 mg/kg]) and two sedatives (chlordiazepoxide [1.78-32 mg/kg] and pentobarbital [1.0-17.8 mg/kg]) in pigeons responding under a 3-component multiple fixed-interval (FI) 300-s schedule maintained by 2-, 4-, or 8-s of food access. We also examine the effects of d-amphetamine [0.32-3.2 mg/kg] and pentobarbital [1.8-10 mg/kg] in rats responding under a similar multiple FI300-s schedule maintained by 2- or 10- food pellet (45 mg) delivery. In pigeons, cocaine and, to a lesser extent, chlordiazepoxide exerted rate-dependent effects that were diminished by increasing durations of food access. The relationship was less apparent for pentobarbital, and not present for d-amphetamine. In rats, rate-dependent effects of pentobarbital and d-amphetamine were not modulated by reinforcement magnitude. In conclusion, some drugs appear to exert rate-dependent effect which are diminished when reinforcement magnitude is relatively high. Subsequent analysis of the rate-dependency data suggest the effects of reinforcement magnitude may be due to a diminution of drug-induced increases in low-rate behavior that occurs early in the fixed-interval.
Topics: Animals; Behavior, Animal; Central Nervous System Stimulants; Chlordiazepoxide; Cocaine; Columbidae; Conditioning, Operant; Dextroamphetamine; Dose-Response Relationship, Drug; Food; Hypnotics and Sedatives; Male; Pentobarbital; Rats; Reinforcement Schedule; Time Factors
PubMed: 21707192
DOI: 10.1037/a0024311 -
Anesthesiology Oct 1984Local rates of glucose utilization in the spinal cord and brain were measured with the 2-[14C]deoxyglucose method in conscious and in paralyzed and mechanically... (Comparative Study)
Comparative Study
Local rates of glucose utilization in the spinal cord and brain were measured with the 2-[14C]deoxyglucose method in conscious and in paralyzed and mechanically ventilated pentobarbital- or 70% nitrous oxide-treated rats. In conscious animal lumbar spinal cord glucose utilization is only 40-50% that of the cerebral cortex and shows little laminar heterogeneity. Pentobarbital reduces and nitrous oxide increases the cerebral glucose utilization of most structures. The effect of paralysis and nitrous oxide analgesia on lumbar spinal cord glucose utilization is quantitatively similar to that produced in brain; 15-25% increases occur in most spinal cord laminae and cerebral structures. In contrast, the 10-20% reduction in spinal cord gray matter metabolism in the paralyzed and pentobarbital-treated animals is considerably less than the 20-50% depression measured in most brain structures. From these data the authors conclude that, relative to that of most cerebral structures, spinal cord metabolism is less sensitive to depression by barbiturates and suggest that differences in the cell populations of these tissues may account partially for this observation.
Topics: Analgesia; Animals; Brain; Glucose; Male; Nitrous Oxide; Oxygen Consumption; Pentobarbital; Rats; Rats, Inbred Strains; Spinal Cord
PubMed: 6486505
DOI: 10.1097/00000542-198410000-00012 -
Psychopharmacology 1982Rhesus monkeys were trained to emit 20 or 30 consecutive responses on one lever following an IM injection of pentobarbital (10 or 18 mg/kg) and the same number of...
Rhesus monkeys were trained to emit 20 or 30 consecutive responses on one lever following an IM injection of pentobarbital (10 or 18 mg/kg) and the same number of consecutive responses on another lever following an injection of saline. The required number of correct consecutive responses in both cases resulted in food delivery. When responding was reliably under the control of the presession injection, the ability of a variety of other compounds to produce pentobarbital-appropriate responding was examined. Diazepam, clobazam, methohexital, pentobarbital, and phenobarbital, given 10 or 20 min before the session, produced dose-related pentobarbital-appropriate responding in each monkey. Ethylketazocine and dextromethorphan produced responding primarily on the saline-appropriate lever, whereas codeine, cyclazocine, dextrorphan, and ketamine resulted in responding that was, on the average, intermediate between that appropriate for pentobarbital and that appropriate for saline. When tested at various times after their injection, methohexital (3.2 mg/kg) and pentobarbital (10 mg/kg) produced pentobarbital-appropriate responding within 10 min. Barbital (56 mg/kg) resulted in pentobarbital-appropriate responding only if at least 1 h intervened between the injection and the experimental session. The discriminative effects of methohexital, pentobarbital, and barbital lasted approximately 20-60, 120-240, and 480-720 min, respectively. The time-course of the discriminative stimulus effects of barbiturates in the rhesus monkey appears to parallel closely other pharmacological actions of these compounds.
Topics: Animals; Barbiturates; Dextromethorphan; Discrimination Learning; Generalization, Psychological; Ketamine; Macaca mulatta; Male; Pentobarbital; Time Factors
PubMed: 6805028
DOI: 10.1007/BF00435273 -
Journal of the Experimental Analysis of... Jul 1984Performances of three rhesus monkeys were reinforced by the oral delivery of pentobarbital and studied as functions of fixed-ratio size and drug concentration....
Performances of three rhesus monkeys were reinforced by the oral delivery of pentobarbital and studied as functions of fixed-ratio size and drug concentration. Pentobarbital solutions and water were concurrently available on identical reinforcement schedules from separate liquid-delivery systems during 3-hour sessions. Under a fixed-ratio 16 schedule of drug availability, a descending series of drug concentrations was tested (4, 2, 1, 0.5, 0.25, 0.125, and 0.0625 mg/ml, followed by a retest at 4 mg/ml). Partial concentration series beginning with the highest concentration were repeated with fixed-ratios of 32 and 64, with a fixed-ratio 128 for two monkeys, and with fixed-ratio 256 for one. At each fixed-ratio value, response rate and number of drug deliveries were inverted U-shaped functions of pentobarbital concentration. Drug intake (mg/kg/session) increased directly with drug concentration. As the fixed-ratio size was increased, the number of liquid deliveries decreased. For each drug concentration, when the numbers of drug deliveries at fixed-ratios of 32, 64, and 128 responses were plotted as percentages of those obtained at fixed-ratio 16, the following orderly relationship emerged: the higher the drug concentration, the less that drug deliveries were decreased by increases in fixed-ratio size. This relationship indicates an increase in reinforcing efficacy with increases in pentobarbital concentration.
Topics: Animals; Dose-Response Relationship, Drug; Macaca mulatta; Male; Pentobarbital; Reinforcement Schedule; Reinforcement, Psychology; Self Administration
PubMed: 6481299
DOI: 10.1901/jeab.1984.42-37 -
Japanese Journal of Pharmacology Sep 1985Stressful stimuli, electric footshock (FS), immobilized-water immersion (IW), and cold-water swimming (CWS), produced analgesia and prolonged the pentobarbital hypnosis...
Stressful stimuli, electric footshock (FS), immobilized-water immersion (IW), and cold-water swimming (CWS), produced analgesia and prolonged the pentobarbital hypnosis as well as morphine and clonidine. Naloxone completely antagonized the analgesic effects of morphine and FS and partially that of IW; however, that of clonidine and CWS were not reversed by naloxone. Naloxone eliminated the hypnosis prolonging effect of morphine and FS, but failed to reverse the effect of clonidine, IW and CWS. Differences in the analgesic and hypnosis prolonging effects and also the respective naloxone sensitivity of each drug and stress suggest the diversity of the underlying mechanisms.
Topics: Analgesics; Animals; Clonidine; Electroshock; Hypnotics and Sedatives; Immersion; Male; Mice; Naloxone; Pentobarbital; Stress, Psychological
PubMed: 4068389
DOI: 10.1254/jjp.39.117 -
The Journal of Physiology Dec 19721. The effects of pentobarbitone (0.05-0.6 mM in saline solution) on the evoked field potentials of in vitro preparations of guinea-pig olfactory cortex were studied.2....
1. The effects of pentobarbitone (0.05-0.6 mM in saline solution) on the evoked field potentials of in vitro preparations of guinea-pig olfactory cortex were studied.2. The evoked field potentials comprised an initial diphasic wave - the lateral olfactory tract (l.o.t.) compound action potential - followed by a surface negative wave (e.p.s.p) of 1-3 mV amplitude and about 10 msec duration. Superimposed on the negative wave were a number of positive peaks (population spikes).3. Pentobarbitone depressed the e.p.s.p. but not the l.o.t. compound action potential. The number and size of the population spikes were progressively reduced as the e.p.s.p. became depressed, indicating a failure of transmission through the cortical relay. The e.p.s.p. depression increased with increasing concentrations of pentobarbitone.4. Pentobarbitone had no effect on the threshold to electrical stimulation of the l.o.t. fibres or on that of the post-synaptic cells to synaptic excitation.5. Post-tetanic potentiation and frequency potentiation were either of normal magnitude or were enhanced in the presence of 0.2-0.3 mM pentobarbitone.6. It is concluded that pentobarbitone probably reduces the output of transmitter from the presynaptic nerve terminals of the olfactory cortex and that this mechanism could be the basis of the depressant action of the barbiturates.
Topics: Action Potentials; Anesthesia; Animals; Depression, Chemical; Electric Stimulation; Electrophysiology; Evoked Potentials; Guinea Pigs; In Vitro Techniques; Limbic System; Neurotransmitter Agents; Pentobarbital; Secretory Rate; Synapses; Synaptic Transmission
PubMed: 4405554
DOI: 10.1113/jphysiol.1972.sp010057 -
Anesthesiology Jan 1983The impact of tolerance on the metabolism of the whole body, skeletal muscle, brain, kidneys, splanchnic region, and heart during prolonged pentobarbital anesthesia was...
The impact of tolerance on the metabolism of the whole body, skeletal muscle, brain, kidneys, splanchnic region, and heart during prolonged pentobarbital anesthesia was evaluated in 80 dogs. Oxygen consumption (VO2) for each organ system and whole body was calculated from measured blood flow rate and the difference in blood oxygen content between arterial and venous blood during four periods of continuous and unvarying deep pentobarbital anesthesia: 0-3 h, 3-6 h, 12-15 h, and 21-24 h. VO2 increased with time in whole body (12%), gastrocnemius muscle (83%), calculated entire skeletal muscle (15%), brain (27%), kidneys (20%), and splanchnic area (10%); it decreased in the heart (20%). In all studies, the electroencephalogram indicated a constant deep burst-suppression level of 2-6 bursts/min and blood pentobarbital levels ranged from 4.5-6 mg/dl. About one-fifth of the increase in gastrocnemius VO2 could be accounted for by the effect of a continuous infusion of succinylcholine, and about two-thirds of the rise in renal VO2 by increased renal function. The decrease in heart VO2 was associated with increased cardiac output and decreased systemic vascular resistance. The sustained increase in metabolism was significant and otherwise unexplained in whole body, skeletal muscle, and the brain; it occurred after 3 h had continued through 24 h of pentobarbital anesthesia. This was presumably due to tolerance, and was manifested as increased metabolism during steady deep anesthesia with unchanged blood levels of pentobarbital rather than as a greater requirement for pentobarbital.
Topics: Anesthesia; Animals; Dogs; Drug Tolerance; Electroencephalography; Lactates; Lactic Acid; Metabolism; Oxygen Consumption; Pentobarbital; Regional Blood Flow; Time Factors
PubMed: 6848014
DOI: 10.1097/00000542-198301000-00004 -
Anesthesiology Jun 1987Barbiturates are often utilized clinically in circumstances in which elevated intracranial pressure is expected. In this study, the mechanism of action of barbiturates...
Barbiturates are often utilized clinically in circumstances in which elevated intracranial pressure is expected. In this study, the mechanism of action of barbiturates was examined in dogs with intracranial hypertension induced by injecting autogenous incubated blood into the chiasmatic cistern. Intracranial pressure and systemic blood pressure were continuously monitored. A single bilateral administration of powdered pentobarbital (2 mg and 0.4 mg) in experimental animals and solid d-glucose (2 mg) in control animals was given into the posterior hypothalamus, pontine reticular formation, or medullary reticular formation when intracranial pressure reached 20-30 mmHg after the blood injection--usually in 3-6 h. The increased intracranial pressure following the experimental subarachnoid hemorrhage was always associated with either intracranial pressure irregularities or concomitant blood pressure variations, suggesting the presence of vasomotor instability. Administration of both 2 mg and 0.4 mg of pentobarbital into the medulla caused a significant (P less than 0.01) decrease of the intracranial pressure to 44 and 65% of control and stabilization of the intracranial pressure irregularities, whereas pentobarbital given at the other sites did not. The blood pressure was also decreased significantly (P less than 0.01) to 80 and 88% of control and the blood pressure variations were stabilized in animals after administration of pentobarbital into the medulla, whereas in those given pentobarbital at the other sites, it was not. The results suggest that, in the presence of elevated intracranial pressure following experimental subarachnoid hemorrhage, the mechanisms of action of barbiturates in reducing the intracranial pressure may result from alleviation of cerebral vasomotor instability by depression of the vasomotor center of the medulla.
Topics: Animals; Dogs; Hypothalamus, Posterior; Injections; Intracranial Pressure; Medulla Oblongata; Pentobarbital; Pons; Pseudotumor Cerebri; Reticular Formation; Subarachnoid Hemorrhage
PubMed: 3592276
DOI: 10.1097/00000542-198706000-00009