Perfusion from cerebral ventricle to cisterna magna in the unanaesthetized cat. Effect of calcium on body temperature

Feldberg, W.; Myers, R.D.; Veale, W. L.

doi:10.1113/jphysiol.1970.sp009069

Cited by 117 publications

(32 citation statements)

References 7 publications

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“…Recently, it has been found that a change in the ratio of sodium to calcium ions in the cerebral ventricles or in the posterior HYPOTHALAMIC IONS AND TEMPERATURE hypothalamus produces consistent changes in body temperature, in the same direction, in several species including the cat (Feldberg, Myers & Veale, 1970;, the rabbit (Feldberg & Saxena, 1970), the monkey (Myers, Veale & Yaksh, 1971) and in the rat (Myers & Brophy, 1971). In each of these species, the fact that the temperature is 37.00 C or thereabouts at birth, would support the view that a mechanism, such as the postulated ionic one for the set-point, is present at parturition although the capacity to thermoregulate against heat or cold may not be adequate .…”

Section: Discussionmentioning

confidence: 99%

Thermoregulation around a new ‘set‐point’ established in the monkey by altering the ratio of sodium to calcium ions within the hypothalamus

Myers¹,

Yaksh²

1971

The Journal of Physiology

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SUMMARY1. The cerebral ventricles of the unanaesthetized monkey were perfused at a rate of 50-100 4td./min with artificial cerebrospinal fluid (c.s.f.) containing 11F0-340 mm excess sodium or 23-9-47-9 mm excess calcium ions. By repeated perfusions, a marked hyperthermia elicited by excess sodium or deep hypothermia by excess calcium was sustained for up to half a day.2. During the sodium-induced hyperthermia or calcium-induced hypothermia, the monkey thermoregulated adequately around the new level of temperature in response to either 50 or 150 ml. water heated to 580 C or chilled to 00 C and given by the intragastric route. Cold water produced a transient hypothermia after which temperature returned to the pre-load level; hot water given in the same way evoked a short-lasting hyperthermia, and again the temperature returned just to the new setpoint level.3. Perfusions at 50 #1./min of isolated areas of the diencephalon by means of push-pull cannulae with a solution containing 110-34-0 mm excess sodium ions or 11L3-47-9 mm excess calcium ions altered the body temperature of the monkey only when the sites of perfusion were located in the mammillary region of the posterior hypothalamus. Following the prolonged hyperthermia produced by excess sodium ions or the deep hypothermia evoked by excess calcium ions in the push-pull perfusion fluid, the monkey thermoregulated around the new temperature level again in response to 150 ml. of either hot or cold water given in the stomach. R. D. MYERS AND T. L. YAKSH perature. When EGTA was perfused directly in the posterior hypothalamus by means of push-pull cannulae, a profound hyper-pyrexia ensued which could be abolished immediately by perfusing a solution of excess calcium at the same diencephalic site.5. During the calcium-induced hypothermia, the heart rate declined but the electrical activity of the cortex was relatively unchanged. Feeding was also elicited in the hypothermic monkey by noradrenaline microinjected at a site in the hypothalamus at which eating was evoked when the body temperature was normal.6. The evidence supports the hypothesis that in the primate, the inborn mechanism which establishes the set-point for body temperature at 370 C is the constancy in the intrinsic ratio between sodium and calcium ions within the posterior hypothalamus. If the set-point is elevated or lowered by a disturbance of the balance between these two cations, the monkey nevertheless can thermoregulate normally around the new level of body temperature.

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Section: Discussionmentioning

confidence: 99%

Thermoregulation around a new ‘set‐point’ established in the monkey by altering the ratio of sodium to calcium ions within the hypothalamus

Myers¹,

Yaksh²

1971

The Journal of Physiology

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“…A change in the ratio of sodium to calcium ions in the artificial cerebrospinal fluid (CSF) perfused through the cerebral ventricles produces consistent changes in body temperature in the same direction in the cat (Feldberg, Myers & Veale, 1970;, rabbit (Feldberg & Saxena, 1970a, b), monkey (Myers, Veale & Yaksh, 1971), rat (Myers & Brophy, 1971) and sheep (Myers, 1974). Feldberg et al (1970) suggested that in homoeothermic animals the constancy of temperature depends on the balance of sodium and calcium ions in the anterior hypothalamus and that calcium ions may act as a kind of 'brake' and prevent the sodium ions from exerting their hyperthermic effect.…”

Section: Introductionmentioning

confidence: 99%

Sodium and Calcium Ions in the Control of Temperature Set‐point in the Pigeon

Saxena

1976

British J Pharmacology

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I The effect of altering the ionic balance of the cerebrospinal fluid (CSF) on cloacal temperature of unanaesthetized pigeons kept at room temperature (20-250C) was examined by injection or infusion of solutions of different ionic composition into a cannulated lateral cerebral ventricle. 2 An increase in the concentration of calcium ions caused a fall in temperature and behavioural sedation. The effects were the same whether the calcium was present as calcium chloride or as the calcium disodium salt of ethylenediamine tetra-acetic acid (CaNa2EDTA). 3 When the concentration of sodium ions in the CSF perfusate was increased by addition of NaCl or that of calcium ions was decreased by addition of Na2EDTA a rise in temperature was often produced but this was not consistent. NaCl sometimes had either no effect or lowered the temperature.Na2EDTA while producing a rise when first injected failed to do so when repeated a few hours, 24 h and often 72 h later. Prolonged infusion of either agent caused intense behavioural excitement leading to death. 4 Potassium ions, like sodium ions, caused a rise in temperature but only when infused continuously. Behavioural excitement was only rarely observed. 5Magnesium produced a fall in temperature. The concentration required was much higher than that of calcium but the hypothermia was more prolonged suggesting a slower elimination of the magnesium ions from the CSF. Magnesium ions caused tremors, nystagmus and ataxia as opposed to sedation caused by calcium. 6 All these were central effects as they were not obtained when the substances were injected intravenously. 7 Since changes in body temperature of the pigeon produced by injection of calcium or sodium ions into the CSF were similar to those seen in various species of mammal, it is concluded that the reiative concentration of these ions within the brain plays an important role in establishing the temperature setpoint in both birds and mammals.

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“…Although the onset of the hyperthermic responses was usually between 1 and 10 min after the injection, the duration of the fever produced was often difficult to assess, especially with larger doses, because of the interference encountered from a non-specific fever of slow onset. This latter fever, which has been described by other workers (Feldberg, Myers & Veale, 1970;Feldberg & Saxena, 1970) and is thought to be due to an unknown pyrogenic factor, normally developed between 1 and 3 h after an injection. At such time the shorter duration hyperthermias produced by lower doses of RX72601 were completed, whilst the rises in temperatures produced by large doses of RX72601 were still in evidence.…”

Section: Intraventricular Injections Of Rx72601mentioning

confidence: 91%

Temperature and Behavioural Responses Induced in the Unanaesthetized Cat by the Central Administration of Rx72601, a New Anticholinesterase

Metcalf

Myers

Redgrave

1975

British J Pharmacology

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The central effects produced by a new anticholinesterase RX72601 injected into the cerebral ventricles or perfused within circumscribed forebrain structures have been investigated in the unanaesthetized cat. When injected into the cerebral ventricles in doses of 1–10 μg, RX72601 produced a dose‐related hyperthermia together with behavioural and autonomic responses. Experiments designed to localize the site or sites of these actions demonstrated that hyperthermia could be produced from several diencephalic sites but that the other effects were not normally produced from these same sites.

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Perfusion from cerebral ventricle to cisterna magna in the unanaesthetized cat. Effect of calcium on body temperature

Cited by 117 publications

References 7 publications

Thermoregulation around a new ‘set‐point’ established in the monkey by altering the ratio of sodium to calcium ions within the hypothalamus

Thermoregulation around a new ‘set‐point’ established in the monkey by altering the ratio of sodium to calcium ions within the hypothalamus

Sodium and Calcium Ions in the Control of Temperature Set‐point in the Pigeon

Temperature and Behavioural Responses Induced in the Unanaesthetized Cat by the Central Administration of Rx72601, a New Anticholinesterase

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