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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The influence of an anaesthetic dose of chlormethiazole (Hemineurin) on blood flow (CBF) and oxygen consumption (CMRO2) in the rat brain was investigated. In spontaneously breathing animals a dose of 160 mg . kg-1 of chlormethiazole, infused i.v., induced a state close to surgical anaesthesia. In paralyzed animals, the same dose decreased CBF and CMRO2 to about 60% of control, an effect similar to that observed after an anaesthetic dose of phenobarbitone. Neither a protective nor a detrimental effect of chlormethiazole could be demonstrated when the drug was given during reversible and pronounced, incomplete ischaemia, as evaluated from the postischaemic tissue concentrations of labile phosphates (PCr, ATP, ADP, AMP) and of lactate and pyruvate. It is concluded that protection in this situation (as earlier shown with phenobarbitone) must, at least partly, be related to other mechanisms than a depression of metabolism.
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PMID:Influence of chlormethiazole on cerebral blood flow and oxygen consumption in the rat, and its effect on the recovery of cortical energy metabolism after pronounced, incomplete ischaemia. 3 16

Studies were conducted in 189 oral surgery out-patients to evaluate the combination of meperidine hydrochloride and diazepam for anesthesia and to determine its effect on the cardiovascular and pulmonary systems. Results showed that neither ventricular cardiac arrhythmias nor clinically significant respiratory depression occurred in the sedated patients; meperidine-diazepam proved to be satisfactory for oral surgical procedures.
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PMID:Evaluation of cardiovascular and pulmonary changes during meperidine-diazepam anesthesia. 4 41

The effect of urethane on hippocampal single unit activity in rats paralyzed with gallamine triethiodide was examined to determine possible influences of urethane as an anesthetic for electrophysiological recordings. With intravenous injections of urethane (1.0 g/kg body weight), hippocampal units responded initially with a substantial decrease in spontaneous firing rate. Activity in some cells recovered partially after a period of approximately 45 min. The activity of the remainder of cells recorded remained depressed for periods of time up to 1.5 hr. Longer periods of depression were observed in some cells. The difference in susceptibility to urethane in the population of hippocampal cells may offer a selective alteration in patterns of spontaneous activity in the hippocampus and systems efferent to the hippocampus. A knowledge of such alterations may prove important in interpreting the results of electrophysiological recording in preparations under urethane anesthesia.
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PMID:Effects of urethane on hippocampal unit activity in the rat. 12 23

Using micropuncture techniques, the author studied the effect of vasopressin on renal function in young rats at three stages of development -- in the middle of the weaning period (22 days), after weaning was over (30 days) and at the beginning of the sexual maturation period (42 days). In the presence of a hypotonic load, a small dose of vasopressin (12 muU/100 g b.w., i.v.) was most effective in the youngest age group, where it reduced the urine flow by 82% both by increasing water reabsorption and by reducing the GFR. In this group, vasopressin lowered the TF/P Na+ ratio and raised the TF/P K+ ratio in the initial part of the distal tubules of the superficial nephrons, but raised water absorption only beyond the initial part of the distal tubules. Vasopressin reduced the urine flow by 72% in 30-day-old rats by raising water reabsorption beyond the initial part of the distal tubules. The only ion to be affected was K+, whose concentration rose in the final urine. In 42-day-old rats the effect of vasopressin was manifested in only mild depression of the GFR. In this age group, as distinct from younger animals, anaesthesia and surgery evidently led to endogenous vasopressin release, so that the small dose of exogenous vasopressin did not significantly influence the test parameters. This is also underlined by the significant difference between the control urine flow of the 42-day-old and the younger rats.
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PMID:The effect of vasopressin on renal function in young rats a clearance and micropuncture study. 13 28

Cardiovascular hazards of laparoscopy performed under local anaesthesia and with room air pneumoperitoneum are not well known. Therefore we have recorded electrocardiogram, arterial blood pressure and central venous pressure in 63 consecutive liver patients undergoing this procedure. Electrocardiographic changes were found in 34 cases, and consisted in transistory tachycardia and bradycardia, ectopic supraventricular and ventricular beats, ST segment depression and flattening of T wave. Blood pressure did not change significantly, but five patients had transitory hypotension during the procedure. Central venous pressure did not vary immediately after inflation, but a significant increase was found during the performance of laparoscopy and it was still observed after deflation. Our findings show that cardiovascular changes during laparoscopy under local anaesthesia are minimal, and that they are probably due to neurogenic factors.
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PMID:Electrocardiogram, arterial and central venous pressure during laparoscopy under local anaesthesia. 14 32

The literature on anaesthesiological studies performed to investigate a possible sparing effect of diazepam on the dosage of muscle-relaxants during anaesthesia is reviewed. Despite some conflicting results it can be concluded that diazepam exerts such an effect, thus allowing between 8 and 30% of the amounts of muscle-relaxants, depending on the type of anesthesia used, to be spared. This conclusion is also supported by the results of pharmacological studies in animals, using the head drop method. The mechanism of this effect is discussed on the basis of the relevant published pharmacological evidence from "in vitro" studies and from both animal and human "in vivo" studies. From these reports it is concluded that diazepam, at therapeutic doses, does not act on neuromuscular transmission and that this sparing effect does not result from direct pharmacological interaction with neuromuscular blocking agents. Some studies indicate a minimal action of the product on the skeletal muscle fibre, but this also is not related to the sparing effect. It is furthermore concluded that his sparing effect of diazepam on the dosage of muscle-relaxants during anesthesia is due to a summation of muscle-relaxant actions exerted at different levels of the nervous system, those of diazepam being mainly exerted at the spinal and brainstem level and consisting in inhibition of polysynaptic reflex activity, enhancement of presynaptic inhibition, and depression of gamma-motoneuron activity.
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PMID:The influence of diazepam on the dosage of muscel-relaxants during anaesthesia. 16 42

Major inhalational anesthetics cause inhibition in the electron transport chain in the region of Complex I resulting in decreased oxygen utilization, inhibition of metabolism of NAD-linked substrates, but not of succinate, inhibition of mitochondrial calcium uptake, and depression of synaptic transmission because of postulated changes in ACh sensitivity or GABA inhibition. Many cellular metabolic effects in CNS and other tissues are secondary to the above. Many metabolic changes noted with anesthetics occur subsequent to activation of the sympathetic nervous system either directly by the anesthetic or by surgical stimulation in the presence of light anesthesia. Many important studies remain to be done.
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PMID:Effects of anesthesia on intermediary metabolism. 16 50

A cumulative dose-response curve for d-tubocurarine based on body weight was determined for 44 infants and children 1 day to 7 years of age during halothane, nitrous oxide and oxygen anesthesia. Depression of thumb adduction was measured. Age difference did not affect the mean dose-effect response. Infants less than 10 days old, however, showed the wideest deviation of responses. When the effect of d-tubocurarine is determined by twitch response, infants and children are more resistant to d-tubocurarine and recover faster than adults from similar levels of neuromuscular depression. Monitoring of neuromuscular function by train-of-four stimulation proved as useful as it is in adults.
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PMID:Re-evaluation of dosage and duration of action of d-tubocurarine in the pediatric age group. 17 Aug 45

The antagonism observed between pressure and anesthesia in intact animals suggests that pressure antagonism may be a promising criterion for identifying the effects of anesthetics which are important to loss of responsiveness. It is therefore of interest to compare the effects of pressure and anesthesia on conduction and on synaptic transmission, which have often been proposed as possible alternative cellular sites of anesthesia. The model used in this study is the isolated rat superior cervical ganglion. Helium pressure (35-103 atm) antagonized partial conduction block of the preganglionic nerve by halothane(0.5 and 1 mM). Helium pressure failed to antagonize the depressant effects of halothane (0.25-0.5 mM) on nicotinic transmission and of halothane or methoxyflurane (0.24 mM) on muscarinic transmission in the ganglion. Pressure itself severely depressed synaptic transmission and added to the depressant effects of the anesthetics. Conduction block as a possible cellular mechanism of anesthesia therefore meets the proposed criterion of pressure reversibility. In contrast, pressure does not antagonize anesthetic depression of excitatory synaptic transmission in the rat superior cervical ganglion.
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PMID:Effects of pressure and anesthetics on conduction and synaptic transmission. 17 76

1. A comparison has been made of the effects of three acetylcholine antagonists--hexamethonium, tubocurarine and pancuronium--on maximal tetani of limb muscles of cats under chloralose anaesthesia. In most experiments, the indirectly stimulated soleus muscle was studied, but observations were also made on the tibialis anterior and flexor digitorum longus muscles. 2. When neuromuscular block was produced by intra-arterial injections of the acetylcholine antagonists, tetanic tension, though depressed in amplitude did not wane and there was little or no post-tetanic relief of the block as judged by the amplitude of subsequent twitches. On the other hand, during similar degrees of block produced by intravenous injections, tetanic tension rapidly waned, and, after the tetanus, transmission was temporarily facilitated, as evidenced by an increase in the amplitude of post-tetanic twitches. 3. Intravenously injected hexamethonium caused complete waning of tetanic tension in doses too small to depress twitch amplitude and which caused only a small depression of peak tetanic tension. In contrast, pancuronium caused only partial tetanic fade even in doses that produced pronounced depressions of twitch and tetanic tensions. The effects of tubocurarine fell between these extremes. 4. The results suggest that depression of peak tension and tetanic fade are independent effects of acetylcholine antagonists. It is postulated that the former is a consequence of block of post-junctional cholinoceptors, whereas the latter arises from an action of pre-junctional cholinoceptors. 5. The results obtained, together with those of other workers, led to the suggestion that transmitter acetylcholine, in addition to evoking the endplate potential, acts on the nonmyelinated nerve terminals in a positive feed-back mechanism that mobilizes transmitter to keep pace with release during high frequencies of stimulation.
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PMID:Tetanic fade during partial transmission failure produced by non-depolarizing neuromuscular blocking drugs in the cat. 18 80


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