Effects of Cooling and Warming of the Common Carotid Arteries on the Brain and Tympanic Membrane Temperatures in the Rabbit

Abstract

The thermal change in the hypothalamus, the thermoregulatory center, of the ex perimental animals has been usually measured by use of a thermocouple or a needle formed thermistor inserted through the skull and the brain parenchyma. However, these procedures may be unsuitable for a longterm, observation of the body temperature because the insertion of the thermodes causes considerably widespread damage of the brain tissues, particularly the hypothalamus.Recording the intracardiac, rectal and muscular temperatures of the rabbit by means of the thermistor equipped on the apex of the venous catheter or of the metal-needle, Yasuda (1-3) of this laboratory has reported the influence of various pyrogenic substances on the temperature. Using the same technique, Takashima (4) has compared the effects of pyrogenic substances in the intact and the liver-damaged rabbits.There exist some reports on the tympanic membrane temperature. Benzinger (5) has chosen the tympanic membrane of a human for the measurement of internal body temperature as close as feasible to the hypothalamic heat center. He has introduced 36-gauge twin wires of copper and constantan into the external auditory canal and has placed the thermoelectric junction of the wires at the tympanic membrane. But little work has been done to study the correlation between the brain temperature and the tympanic membrane temperature. The present experiments have been designed to deter mine whether the tympanic membrane temperature changes in parallel with the hypo thalamic temperature or not. In these experiments a decline of the tympanic membrane and brain temperatures was produced by cooling the common carotid arteries or by the administration of some hypothermic agents. An elevation of the temperature was produced by the carotid warming or by the administration of pyrogenic substances. Moreover, the influences of the carotid cooling and warming on behaviors, respiration, blood pressure and heart rate were studied. METHODSUnanesthetized male albino rabbits, weighting 2.0 to 2.5 kg, were used in the ex periments. All experiments were performed at a room temperature maintained always

Considerations for the measurement of core, skin and mean body temperatures

“…Therefore, whilst true tympanic-membrane temperature can track blood and oesophageal temperatures (Fig. 5: Tanabe and Takaori, 1964;Piironen, 1970;Molnar and Read, 1974;Shiraki et al, 1986Shiraki et al, , 1988Brinnel and Cabanac, 1989;Cotter et al, 1995;Sato et al, 1996), that blood was acting as a brain coolant (Hayward and Baker, 1968;Fig. 8).…”

Evidence of a relationship between asymmetries in tympanic membrane temperature and lateralised sensory preferences

“…It is known that such infrared thermometers are quite accurate (Imamura et al, 1998). Tympanic membrane temperature reflects brain temperature with high accuracy in animals (Baker, Stocking, & Meehan, 1972;Tanabe & Takaori, 1964) as well as humans (Benzinger, 1959;Brinnel & Cabanac, 1989;Cabanac, 1993;Mariak, Lewko, Jadeszko, & Dudek, 1994;Ogawa, 1994). Tanabe and Takaori (1964) in the rabbit, and Baker et al (1972) in the cat and monkey, have observed that TMT fluctuates in parallel with the hypothalamic temperature.…”

Effect of acetazolamide on cerebral blood flow and tympanic temperature in healthy subjects and patients with subacute subarachnoid haemorrhage

“…Randall et al (1963) have reported that the cat hypothalamus was cooled by arterial blood flow while the tympanic membrane was warmed by the latter. On the other hand, Tanabe and Takaori (1964) in the rabbit and Baker et al (1972) in cat and monkey have observed that T ty fluctuated in parallel with the hypothalamic temperature. Shiraki et al (1988) have maintained that there is a discrepancy between changes in lateral ventricular and white matter temperatures and those in T ty from observations in a patient with a pineal tumor.…”

“…Tympanic membrane temperature (T ty ) has been shown in many reports to reflect brain temperature with high accuracy in animals (Tanabe et al 1964;Baker et al 1972) as well as in humans (Benzinger 1959;Hirata et al 1988;Brinnel and Cabanac 1989;Cabanac 1993;Mariak et al 1994;Ogawa 1994), if measured appropriately. There have also been studies demonstrating a close relationship between CBF and T ty (Nishita 1993;Ogawa et al 1993;Umeyama et al 1995).…”