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Biomedical subjects

K E Cooper

Publications and source records attributed to K E Cooper.

At least 91 records · Page 5Linked to original sources
PubMed1977

Effect of prostaglandin, pyrogen and noradrenaline, injected into the hypothalamus, on thermoregulation in newborn lambs.

Thirteen newborn lambs were implanted stereotaxically with an array of 4 guide tubes positioned bilaterally so that their tips lay above various hypothalamic loci. At postnatal ages 50-70 h, rectal temperature was monitored, and bilateral 1 microliter injections were made into the hypothalamus. Prostaglandin E1 (0.2 microgram) and prostaglandin E2 (0.2-2.0 microgram) did not cause fever on any occasion though injections were made into 44 sites throughout the hypothalamus. Nevertheless, lambs that did not develop fever following central injection were often, if sensitized by bacterial pyrogen given earlier able to develop fever after intravenous injection of bacterial pyrogen. Infusion of a bacterial pyrogen (S. abortus equi, 0.2 microgram) into these same sites caused fever only when injections were made into the anterior hypothalamic/preoptic area (AH/POA). Eight lambs were placed in a 10 degrees C environment and noradrenaline was injected. Rectal temperature fell by 0.5-1.4 degrees C after 7 bilateral injections into the AH/POA, but 9 injections into other hypothalamic areas caused little temperature change. When 6 lambs were placed at a temperature of 30 degrees C and noradrenaline was injected, no consistent temperature changes were observed after microinjection into the AH/POA or other parts of the hypothalamus.

Animals↗
PubMed1977

Cardiovascular effects of fever in the ewe and fetal lamb.

Ewes carrying fetuses with permanently implanted cannulas developed fevers following intravenous injections of bacterial pyrogen (1 microng). During the rising phase of the fever, maternal heart rate increased, but no consistent changes in mean arterial blood pressure (MABP), arterial pH, PO2, or PCO2 were observed during the course of the fever. Fetal temperature, which was initially 0.3 to 0.8 degrees C. higher than maternal temperature rose in parallel with the ewe's temperature. During the maternal fever, fetal MABP, pH, PO2, and PCO2 remained unchanged, but on several occasions the fetal heart rate developed irregularities that persisted after the fever had subsided. These observations suggest that maternal fever does not appear to have adverse effects on fetal oxygenation but has a variable effect on cardiovascular function.

Animals↗
PubMed1977

Alcohol, respiration, skin and body temperature during cold water immersion.

Subjects who had not been exercising, were immersed for 20 min in water at 13 degrees C after ingestion of alcohol. During the immersion period, total ventilation, end-tidal PCO2, rectal temperature, aural temperature, and mean skin temperature were recorded. Control experiments were carried out at the same water temperature. Blood samples (3 ml), taken immediately before the immersion period, were analyzed by gas liquid chromatography. The mean blood alcohol level was 90+/-11.2 mg-(100 ml)-1. There was no significant difference in ventilatory responses, rectal temperatures, aural temperatures, or mean skin temperatures achieved during the two cold water immersions. It would appear that for a 20-min immersion at 13 degrees C, relatively high blood alcohol levels do not affect ventilatory responses or increase body heat losses.

Alcohol Drinking↗
PubMed1976

Effects of atropine, injected into a lateral cerebral ventricle of the rabbit, on fevers due to intravenous leucocyte pyrogen and hypothalamic and intraventricular injections of prostaglandin E1.

1. Cholinergic synapses in the hypothalamus may transmit information in those thermoregulatory pathways which function to raise body temperature. The effect of atropine, administered intracranially, on the febrile response to intravenous leucocyte pyrogen or intracranial prostaglandin E1 was therefore examined in conscious rabbits. 2. In rabbits exposed to a thermoneutral environment, micro-injections of PGE1, into the anterior hypothalamus, intraventricular injections of PGE1, and intravenous injection so leucocyte pyrogen all caused fever accompanied by vasoconstriction in the ears and reduced respiratory rate. Intraventricular injection of 200 mug atropine during such fevers attenuated their development. This was due to the activation of heat loss mechanisms through vasodilatation in the ears and an increase in the frequency of respiration. This suggests a similarity in the pattern of neuronal activity evoked by PGE1 and leucocyte pyrogen, at least at the site(s) where atropine directly or indirectly exerted its effect and in the efferent pathways from this site. 3. In rabbits exposed to a cold environment, intraventricular injection of PGE1 caused fever through the activation of shivering accompanied by increased O2 consumption. Intraventricular injection of atropine during the development of fever caused an inhibition of shivering accompanied by increased O2 consumption. Intraventricular injection of atropine during the development of fever caused an inhibition of shievering and a decrease in O2 consumption so that temperature ceased to rise and returned to normal. 4. During fever, reversal by atropine of the increased heat conservation of rabbits in a neutral environment, and of their increased heat production in a cold environment adds further support to the concept that cholinergic synapses provide an important link in central temperature-rasising pathways.

Animals↗
PubMed1976

The effect of noradrenaline, injected into the hypothalamus, on thermoregulation in the cat.

1. Noradrenaline (NA) was microinjected into the anterior hypothalamic/preoptic area(AH/POA) of unanaesthetized cats held at ambient temperatures of 10, 22 or 35 degrees C. Loci in which injection of NA caused body temperature changes were also found to be sensitive to the febrile action of PGE1. 2. At all ambient temperatures, NA caused a dose-dependent fall in body temperature. However the mechanisms by which these temperature changes were brought about varied at different ambient temperatures. In cats maintained at the higher ambient temperature, NA activated heat loss mechanisms whereas in the cats maintained in the 10degrees C environment, the major effect of NA injection was an inhibition of heat conservation and heat production mechanisms. 3. We conclude that NA acts in cats not only as an inhibitor of heat conservation and production, but also acts in an excitatory manner on an active heat loss pathway within the AH/POA.

Animals↗
PubMed1976

The effect of noradrenaline and 5-hydroxytryptamine injected into a lateral cerebral ventricle, on thermoregulation in the new-born lamb.

1. Respiratory frequency, shivering, ear skin temperatures and rectal temperatures were observed following intraventricular injections of noradrenaline (NA), 5-hydroxytryptamine (5-HT) and saline (NaCl) into new-born lambs exposed to ambient temperatures of 4, 21, or 30 degrees C. 2. Intraventricular NA caused respiratory rate to decrease and body temperature to increase in the 30 degrees C environment. At 21 degrees C, it increased ear skin temperature but did not significantly affect rectal temperature. At 4 degrees C, NA decreased shivering and rectal temperature fell. 3. 5-HT elevated respiratory rate in the 30 degrees C environment and increased ear skin temperature in the 21 and 4 degrees C environments. In the 4 degrees C environment rectal temperature decreased. 4. In general, the change in rectal temperature was related to the dosage of drug administered. Control injections of NaCl had no significant effect on any of the variables measured. 5. The monoaminergic pathways involved in thermoregulation in the new-born lamb appear to be organized in a manner similar to that of the adult sheep and are functional at birth.

Animals↗
PubMed1976

Observations on the effect of salicylate in fever and the regulation of body temperature against cold.

Prostaglandins appear to be mediators, within the hypothalamus, of heat production and conservation during fever. We have investigated a possible role of prostaglandins in the nonfebrile rabbit during thermoregulation in the cold. Shorn rabbits were placed in an environment of 20 degrees C, and rectal and ear skin temperatures, shivering and respiratory rates were measured. A continuous intravenous infusion of leucocyte pyrogen was given to establish a constant fever of approximately 1 degree C, and after observation of a stable febrile temperature for 90 min, a single injection of 300 mg of sodium salicylate, followed by a 1.5 mg/min infusion was then given. After the salicylate infusion was begun, rectal temperature began to fall, and reached nonfebrile levels within 90 min. Shivering activity ceased, respiratory rates increased, and in two animals, ear skin temperature increased. When these same rabbits were placed in an environment of 10 degrees C, at a time they were not febrile, and an identical amount of salicylate was given, rectal and ear skin temperatures, shivering and respiratory rates did not change. These results indicate that prostagladins do not appear to be involved in heat production and conservation in the nonfebrile rabbit.

Animals↗
PubMed1976

Changes in body temperature produced by prostaglandins and pyrogens in the chicken.

Bacterial pyrogen from S. abortus equi (SAE) was injected into the wing veins of chickens. Following injection of 0.05-0.5 mug SAE, body temperatures did not change significantly, whereas 2.0 or 10 mug of pyrogen caused falls in body temperature of 0.56 +/- 0.10degrees C and 1.1 +/- 0.21degrees C (mean +/- SE, n=5). The temperature falls were accompanied by a flushing of the comb and an increase in respiratory rate and were not antagonized by 1.0 g of acetylsalicylic acid (ASA) given orally. The injection of SAE (0.1 mug in 1 mul) into the anterior hypothalamus produced fevers averaging 1.24 +/- 0.07 degrees C (n=9) which were antagonized by oral ASA. Injections of SAE at other brainstem loci produced no temperatur changes. Seven chickens were also injected with 0.1 mug PGE in 1.0 mul into the anterior hypothalamus, and they developed fevers averaging 0.90 +/- 0.16 degrees C. The results support the concept that prostaglandins may be involved in fever in chickens but suggest that the action of pyrogen injected intravenously may be different from that following its injection directly into the hypothalamus.

Animals↗
PubMed1976

Respiratory and other responses in subjects immersed in cold water.

Subjects have been immersed in water at 27 degrees C and 10 degrees C and while immersed their respiratory rates, minute volumes, and end-tidal PCO2 levels were measured. Measurements were made with the subjects at rest, exercising at approximately 0.8 liter oxygen-min-1, and very vigorously at 1.8-2.0 liters oxygen-min-1. Immersion in the cold water caused an increase in respiratory rate and a fall in end-tidal PCO2. At the moderate rate of exercise the hyperventilation persisted in relation to the oxygen demand and there was still a significant reduction in end-tidal PCO2. At the greatest rates of exercise, the end-tidal PCO2 did not differ from that obtained in similar rates of exercise in warm water. Preheating the subject in a sauna so as to increase skin temperature, with minimal change in body temperature, greatly attenuated the ventilatory and end-tidal PCO2 responses to cold water immersion. The significance of these findings is discussed.

Carbon Dioxide↗
PubMed1976

Temperature gradients at various points within the human pelvis as measured during laparoscopy.

Temperatures have been measured during pelvic laparoscopy, under general anesthesia, in 59 women. Temperatures on the serosal surface of the rectum, the mesovarium, the ovarian arteries and the surface of the external iliac artery have been compared with the temperature deep in the rectal cavity on the rectal mucosa. The mean temperatures recorded at all sites within the pelvic cavity were lower than the mean temperatures recorded on the rectal mucosa. The mean differences between rectal mucosa and the other pelvic sites are: rectal mucosa -0.20 +/- standard error of the mean (SEM) 0.03C, mesovarium -0.28 +/-SEM 0.04C, ovarian artery -0.35 +/- SEM 0.05C and external iliac artery -0.44 +/- SEM 0.06C. All differences are highly significant from zero and do not appear to be related to the time from the onset of anesthesia, the temperature of the gas used to fill the abdominal cavity, the time from the last menustrual period and any pathology present in the pelvis. The results are consistent with a previous suggestion, by Grayson,2 that the human rectal mucosa may be an organ of heat production and that arterial blood within the pelvis may be precooled by counter current heat exchange with veins draining cold blood from the extremities.

Body Temperature↗
PubMed1975

Temperature responses of lambs after centrally injected prostaglandins and pyrogens.

It has been proposed that pyrogens may produce their febrile response by the release of prostaglandins in the hypothalamus. To test this theory, prostaglandin E1 (PGE1) was injected into a lateral ventricle in dosages of 2-200 ug into conscious newborn lambs, ages 4-168 h. Fiifteen of 40 injections were followed by rises in rectal temperature but the remainder were followed either by no change or by falls. Temperature responses did not appear to be related to age and a variation in responses to the same dosage of PGE was often observed. Some lambs were able to develop fevers in response to intravenous bacterial pyrogen yet did not develop fever after intraventricular PGE 1. Intraventricular bacterial pyrogen (3 ng) produced no change in body temperature, whereas three of four injections of 300 ng pyrogen caused fever. The results suggest that the newborn lamb may be able to develop a fever independently of the central involvement of PGE1. Alternatively, the intraventricular approach may not be useful for the study of the central control of body temperature in the newborn lamb.

Age Factors↗