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PubMedDate not supplied

Intravenous lidocaine does not cause shivering-like tremor or alter thermoregulation.

We tested the hypotheses that systemic absorption of epidural lidocaine: (1) contributes to the shivering-like tremor seen during epidural anesthesia by causing central nervous system disinhibition of spinal reflexes, or (2) activates or alters thermoregulatory mechanisms. In a double-blind, placebo, cross-over study, nine healthy volunteers were given intravenous lidocaine (or saline) to approximate the plasma levels of lidocaine achieved during epidural anesthesia for major abdominal surgery. Five volunteers were studied in a warm room (to test for nonthermoregulatory tremor), and four volunteers were studied in a cold room (to test the effects of lidocaine on normal thermoregulation). Central temperatures, peripheral vasoconstriction, tremor and clonus were unaffected by intravenous lidocaine. We conclude that the systemic absorption of epidural lidocaine does not contribute to tremor or shivering by these mechanisms.

Adult↗
PubMed1988

Threshold for shivering in aerobic and anaerobic muscles in bantam cocks and incubating hens.

Electromyographic activity (EMG) from the musculus pectoralis (breast muscle), m. iliotibialis (thigh muscle) and m. gastrocnemius (leg muscle), cloacal temperature (Tb) and O2 consumption were measured in bantam cocks (Gallus domesticus) exposed to different ambient temperatures (Ta). The same parameters were measured in bantam hens incubating eggs artificially thermoregulated to 40 degrees and 25 degrees C (Te). EMG activity appeared in thigh and leg muscles at Ta below 32 degrees C (Tsh). This temperature probably represents the thermoneutral temperature (TNT) of the cock. EMG activity in breast muscles appeared at Ta below 20 degrees C, or 4 degrees C below the lower critical temperature (Tc). All muscles were quiet when the hen incubated 40 degrees C egg at Ta = Tsh. When Te was abruptly changed to 25 degrees C, EMG activity in the iliotibialis muscle appeared 3 min before the activity in the pectoralis muscle. Tb dropped from 41.2 degrees to 40.6 degrees C in 14 min. When Te was returned to 40 degrees C, the EMG activity in the pectoralis muscle disappeared almost at once, while the iliotibialis muscle was active until Tb returned to normal. Aerobic muscles seem to be responsible for shivering thermogenesis between Tc and Tsh, while anaerobic muscles are recruited at lower Ta or when the heat loss during incubation becomes severe.

Aerobiosis↗
PubMed1982

Photoperiod-induced changes in temperature-metabolism curve, shivering threshold and body temperature in the pigeon.

A short photophase combined with cold-acclimation changed the shivering threshold of the pigeon from 21 to 14 degrees C. The change of critical temperature was also found in the temperature-metabolism curve. A long photophase both alone and combined with warm-acclimation induced a reduction of body temperature to a lower level (about 2 degrees C) at all ambient temperature, ranging from 5 to 40 degrees C.

Acclimatization↗
PubMed2002

Comparative non-shivering thermogenesis in adjacent populations of the common spiny mouse (Acomys cahirinus) from opposite slopes: the effects of increasing salinity.

We compared non-shivering thermogenesis between two adjacent populations of the common spiny mouse Acomys cahirinus from different habitats, in relation to increasing salinity. Individuals were captured from the north- and south-facing slopes of the same valley, that represent "Mediterranean" and "desert" habitats, respectively. We hypothesized that the two populations of mice would differ in their thermoregulatory capacities, reflecting their need to cope with the environmental stress in each habitat. We measured resting metabolic rate by recording oxygen consumption, body temperature and response to an injection of exogenous noradrenaline. Mice were maintained on diets with increasing levels of salt intake to examine their abilities to cope with increasing osmotic stress. Mice from north-facing slopes generally had a higher resting metabolic rate and a higher increase in oxygen consumption in response to noradrenaline than mice from south-facing slopes. Increasing salinity decreased resting metabolic rate values, body temperature, and oxygen consumption in response to noradrenaline in both populations, and diminished slope-dependant differences. We suggest that these differences could be a result of an ongoing adaptive process to different climatic conditions, typical of the Mediterranean region, that are a demonstrable example of evolution in action.

Animals↗
PubMed1985

Response to cold in the blue fox and raccoon dog as evaluated by metabolism, heart rate and muscular shivering: a re-evaluation.

Oxygen consumption (ml kg-0.75/min) in relation to ambient air temperature at or below the lower critical temperature (Tlc) of the winter-furred raccoon dog (+10 degrees C) and the blue fox (-6 degrees C) is described by the equations y = 14.8-0.28x and y = 7.5-0.20x, respectively. Muscular shivering activity (integrated EMG) of both species increased below thermoneutrality parallel with increasing oxygen uptake and heart rate. Seasonal changes in measured metabolic parameters were evident for both species. The results suggest that the overall body insulation or the metabolic response to cold are not essentially worse in the raccoon dog as compared with the blue fox. It is concluded that earlier speculations of surprisingly wide thermoneutral zone and very low Tlc of the Arctic fox are not evident for the blue fox.

Animals↗
PubMed1999

Disinhibition of lower midbrain neurons enhances non-shivering thermogenesis in anesthetized rats.

UNLABELLED: The hypothesis that the lower midbrain, specifically in and around the retrorubral field (RRF) and/or rubrospinal tract (rs), contains a tonic inhibitory mechanism on non-shivering thermogenesis (NST) was examined in urethane-anesthetized rats. It has been proposed that removal of the tonic inhibitory mechanism in the lower midbrain causes body temperature increase through disinhibition-induced activation of the central sympathetic nervous system. The present experiments were carried out to examine whether and where the proposed midbrain region contains cell bodies that tonically inhibit the NST, and if so, whether they receive any influence from the hypothalamus. Male Wistar rats were anesthetized with urethane (1. 0-1.2 g/kg, i.p.), and various agents were microinjected into the RRF and rs areas of one side before and after knife-cut in the other side of the lower midbrain or isolation of the hypothalamus from the midbrain. Changes in interscapular brown adipose tissue (IBAT), rectum, and tail skin temperatures were monitored. RESULTS: (1) unilateral midbrain procaine increased IBAT and rectal temperatures only after un-injected side of the midbrain had been pre-transected. (2) Effective midbrain sites for procaine to increase IBAT and rectal temperatures was laterally extended. (3) Tetrodotoxin microinjected into the midbrain site where procaine increased IBAT and rectal temperatures also raised both temperatures. (4) l-glutamate decreased IBAT and rectal temperatures when microinjected into one of the most inner midbrain area of procaine-sensitive sites without affecting tail skin temperature. (5) Isolation of the hypothalamus from the lower midbrain did not affect midbrain procaine-induced IBAT and rectal temperature increases. These results suggest that neurons that tonically inhibit the NST are located in the area close to the midline adjacent to the RRF and rs, and that the integrity of the neurons to tonically inhibit the NST is not affected by disconnecting the hypothalamus from the midbrain.

Anesthesia↗
PubMed2003

[Fever-shivers reaction and standard platelet concentrates transfusion: a prospective study].

Fever-shivers reaction (FSR) is the most frequent transfusion immediate incident related to platelet transfusions. The aim of our prospective study was to assess the frequency of the different immediate incidents, especially the frequency and the causes of the FSR, observed during the transfusion of standard platelet concentrates (SPC). For each FSR, analysis of causes included: a bacterial culture of the implicated SPC, a blood culture and HLA antibody screening (lymphocytotoxicity assay) among the patients. In the study period, 34 patients were followed during 74 transfusions. Ten immediate incidents were noted; FSR: N = 8, erythema-urticaria: N = 1 and nausea-vomit: N = 1. The FSR was observed in 6 patients who received 56 SPC. Analysis of causes of this reaction revealed that: HLA antibodies were present in one patient; bacterial contamination was not found neither among the patients nor in the implicated SPC, and the risk of the FSR occurrence rose with increased storage time of the SPC transfused. Indeed, a significant difference was noted between the mean age of the SPC implicated in the FSR and the mean age of those not implicated (P = 0,0028). In conclusion, the FSR is a frequent incident observed during SPC transfusions. In the majority of cases, the cause of this reaction was not identified. Further studies will be necessary to better understand the physiological mechanisms of the FSR.

Adolescent↗
PubMed1983

The effect of cooling on breathing and shivering in unanaesthetized fetal lambs in utero.

The effects of cooling have been studied in chronically instrumented unanaesthetized fetal lambs of 106-132 days gestation. Cold stimulation of cutaneous thermoreceptors by means of a coil placed around the fetus in the amniotic cavity induced continuous breathing which was associated with high-voltage electrocortical activity throughout the cooling period. Direct internal cooling by means of an intragastric cooling coil did not alter fetal breathing or sleep-state patterns. Shivering occurred in response to both external and internal cooling, and this response was present as early as 106 days gestation, well before the appearance of high-voltage sleep. In older fetuses there was evidence of a reduction in thermoregulatory responses during low-voltage electrocortical activity, but not of the complete suspension of thermoregulation characteristic of low-voltage (r.e.m.) sleep seen in mature animals. It is concluded that deep regular breathing associated with high-voltage electrocortical activity can be induced by cold stimulation of cutaneous thermoreceptors, but not by a reduction in core temperature alone. Furthermore, fetal responses to cooling are present as early as 106 days gestation.

Animals↗
PubMed1982

Shivering thermogenesis and glucose uptake by muscles of normal or diabetic rats.

Acute cold exposure of normal rats (4 degrees C for 24 h) increased food intake, reduced plasma glucose and liver glycogen, caused a small increase in plasma free fatty acids, and lowered serum insulin concentration by 50%. In fasted rats, cold raised fatty acid levels twice as high as in fed. In mild diabetes (40 mg/kg streptozotocin iv) cold reduced glucose levels in blood and urine, but in severe diabetes (90 mg/kg) cold aggravated hyperglycemia and ketonuria. Changes in muscle glucose utilization were also studied, after evisceration (functional hepatectomy) of rats from each group. Uptake was calculated from the fall in plasma glucose concentration during the 4-h period after a load of 50% glucose iv. Cold normally increased uptake 67%, but it failed to do so in fasted rats. In diabetic rats, cold enhanced uptake, but only if the disease were mild or insulin controlled. Sensitivity of uptake to insulin was unaffected by cold. The results suggest that shivering thermogenesis, like exercise, can promote glucose uptake by skeletal muscle, if enough insulin is present to prevent excess mobilization of lipid substrates.

Animals↗
PubMed1985

Influence of menstrual cycle on shivering, skin blood flow, and sweating responses measured at night.

In 10 women, external cold and heat exposures were performed both in the middle of luteal phase (L) and in the early follicular phase (F) of the menstrual cycle. Serum progesterone concentrations in L and F averaged 46.0 and 0.9 nmol X l-1, respectively. The experiments took place between 3:00 and 4:30 A.M., when the L-F core temperature difference is maximal. At neutral ambient temperature, esophageal (Tes), tympanic (Tty), rectal (Tre), and mean skin (Tsk) temperatures averaged 0.59 degrees C higher in L than in F. The thresholds for shivering, chest sweating, and cutaneous vasodilation (heat clearance technique) at the thumb and forearm were increased in L by an average of 0.47 degrees C, related to mean body temperature [Tb(es) = 0.87Tes + 0.13 Tsk] and to Tes, Tty, Tre, or Tsk. The above-threshold chest sweat rate and cutaneous heat clearances at the thumb and forearm were also enhanced in L, when related to Tb(es) or time. The metabolic rate, arm blood flow, and heart rate at thermoneutral conditions were increased in L by 5.0%, 1.1 ml X 100 ml-1 X min-1, and 4.6 beats X min-1, respectively. The concomitant increase in threshold temperatures for all autonomic thermoregulatory responses in L supports the concept of a resetting of the set point underlying the basal body temperature elevation in L. The effects of the increased threshold temperatures are counteracted by enhanced heat loss responses.

Analysis of Variance↗
PubMed1985

Shiverer gene maps near the distal end of chromosome 18 in the house mouse.

Several mouse mutations cause unstable locomotion, tremor, seizures, and a reduced lifespan because of deficient myelin formation in the central nervous system. Mutant alleles at the shiverer (shi) locus are the only ones in this series with a selective molecular defect, namely, in myelin basic proteins (MBPs), which are virtually absent in shi homozygotes and 50% reduced in heterozygotes. In the present study, backcross and intercross matings indicate recombination of 21.2 +/- 3.3% between myelin deficient, shimld, and fused phalanges, syfp, a marker near the middle of chromosome 18. Recombination of shimld with twirler (Tw), a marker near the centromere, is 45.7 +/- 4.9%. Thus, the shi locus maps near the distal end of mouse chromosome 18 and is the first available marker for this region. Given the evidence of other workers that an MBP locus maps to the same mouse chromosome, and that part of this chromosome may be syntenic with an MBP-PEPA region on human chromosome 18, it is likely that shi is in or near an MBP gene.

Animals↗
PubMed2000

Shivering in a thoroughbred mare.

An 11-year-old mare presented with neuromuscular deficits and what resembled shivering in the left hind limb. On necropsy, there was no evidence of denervation atrophy of the left hind gastrocnemius muscle. The spinal cord had a small, right-sided lesion at C3-C4 and C4-C5. Tests for equine herpesvirus-1 and Sarcocystis spp. were negative.

Animals↗
PubMedDate not supplied

[Tramadol hydrochloride in the treatment of postoperative shivering].

A double blind study of the therapeutic effect of the opioid tramadol hydrochloride (Gruenenthal, Germany) in the treatment of postoperative trembling was undertaken in 2 groups of patients (50 patients in each) versus that of placebo. The results obtained denoted that tramadol at 1-2 mg/kg arrested completely the postoperative trembling or cut significantly its intensity in 49 (98%) patients. Such high efficiency of tramadol as compared to that of other opioids can be explained by its dual mechanism of action. The dependence of an effective tramadol dose on intensity of shivering and on degree of impaired temperature hemostasis was demonstrated. A comparison of hemodynamic parameters observed before and after the administration of tramadol did not reveal any valuable changes in arterial pressure or cardiac beat rate. Mildly intensified sedation was registered in 17 patients, which is typical of all opioids.

Abdomen↗
PubMed1989

The effect of warm irrigating fluids on the incidence of shivering during transurethral resection of the prostate (TURP).

Twenty-four unpremedicated patients of ASA class II or III undergoing TURP were given esia with 10 mg of tetracaine at level L3-4 or L4-5. These patients were randomly given "warm" or "ambient temperature" irrigating fluids. Those with irrigating fluids of temperature between 25.5 degrees C and 33 degrees C were arranged as Group 1 and those of temperature between 21.5 and 23 degrees C as Group 2. The results failed to show that the incidence of shivering could be decreased by the use of warm irrigating fluids.

Aged↗
PubMedDate not supplied

[The initiation of cold shivering during the local heating of the rat hypothalamus under immersion hypothermia].

A local artificial heating of the hypothalamic centre of thermoregulation in rats subjected to immersion cooling to a deep hypothermia activated a shivering. The data obtained suggest that one of the reasons of disorders in the organism thermoregulatory functions under conditions of a deep hypothermia involves a direct effect of the cold upon the thermoregulation centre in the hypothalamus.

Animals↗
PubMed2000

Neurosteroid progesterone is up-regulated in the brain of jimpy and shiverer mice.

Concentrations of neurosteroids have been measured in the brains of postnatal myelin mutants jimpy (jp) and shiverer (shi) mice and of their normal controls. Progesterone (PROG) concentrations were increased more than threefold in the brains of mutant mice. Marked astroglial reaction occurs in the brains of jp mice and to a much smaller extent in shi ones. Whereas the mitochondrial benzodiazepine/diazepam binding inhibitor (DBI) receptor (MBR) was below the immunohistochemical detection limit in normal mice (except in the choroid plexus and ependyma cells), it was significantly expressed in many reactive astrocytes of jp and shi mice brains. DBI-like peptides, investigated either by immunohistochemistry or by radioimmunoassay, were expressed to similar extents in mutant and control mice. Reversed-phase HPLC indicated that DBI-like peptides were almost exclusively of the triakontatetraneuropeptide size. It was concluded that the increased expression of MBR (involved in the intramitochondrial delivery of cholesterol to P450scc) likely accounts for the large PROG content in mutant mice brain. The role of PROG in myelin repair is discussed.

5-alpha-Dihydroprogesterone↗
PubMed1980

Central myelin in the mouse mutant shiverer.

The spinal cord, optic nerves, and cerebellum of the mouse mutant Shiverer were examined by electron microscopy of thin sections. Although central nervous system myelin is grossly deficient in amount, none of its basic structural elements are missing. Regions of compact myelin can be found composed of several layers of alternating major dense lines and intermediate lines repeating with normal periodicity. The "radial component" consisting of periodic thickenings of the intermediate line aligned through several lamellae was also identified. Axoglial junctions characteristic of the type found in paranodal regions are present in greater than normal numbers but occur in aberrant locations. Myelin sheaths have marked reduced numbers of lamellae, which often contain cytoplasm, terminate in cytoplasmic "loops" within and around myelin sheaths, and do not completely encircle axons. In addition, membranous debris appears within neuronal and glial profiles, suggesting some degree of myelin breakdown. Thus, the protein lacks in this mutant appear not to be associated with discrete deficiencies of specific structural components but rather with a variety of quantitative changes and irregularity of form.

Animals↗