RESPONSES OF COLD- AND WARM-ADAPTED DOGS TO INFUSED NOREPINEPHRINE AND ACUTE BODY COOLING

Oxygen consumption, heart rate, and colonic, pinna, and paw temperatures were recorded continuously in warm-adapted (W-A) and cold-adapted (C-A) dogs anesthetized with pentobarbital sodium (30 mg/kg), paralyzed with Flaxedil (5 mg/kg per hr), and mechanically ventilated. The dogs were infused with norepinephrine (1.25 µg/kg per min) for 20 min at 30 C and after 45 min of acute cold exposure to 5 C. Oxygen consumption of C-A dogs increased with a slight increase in the heart rate during the initial 18–20 min of body cooling. O2 consumption decreased continuously during cold exposure in W-A dogs. Calorigenic effects of infused noradrenaline were similar in C-A and W-A dogs at 30 C and 5 C. Heart rate increased in W-A dogs at 30 and 5 C. These results show that nonshivering thermogenesis is well developed by cold acclimation in dogs, and suggest that the increase may be due to an increase in noradrenaline in blood rather than to increased sensitivity of the animals to the calorigenic effects of noradrenaline.

VIRUS CULTURE STUDIES IN NON-GONOCOCCAL URETHRITIS

Specimens of urethal discharge and scrapings of the urethra from 45 men with non-gonococcal urethritis have been studied for virus content. Human amnion and monkey kidney cell cultures were inoculated. Various temperatures of incubation were used. Specimens were also inoculated into the yolk sac of seven-day fertile eggs. No cytopathic changes were detected in any specimen examined after direct incubation or after passage. No elementary bodies were seen in stained sections of yolk sacs. Haemagglutination and haemadsorption tests were negative. Paired sera from 21 cases were available for antibody titre study. Estimations of urethral temperature and pH were made. The cause of non-gonococcal urethritis remains to be discovered.

ALVEOLAR CAPILLARY TEMPERATURE COMPARED WITH AORTIC AND BRONCHIAL WEDGE TEMPERATURES

Temperature for gas exchange in the alveolar capillaries was determined by the helium-argon method in nine dogs over a range of body temperatures from 37–42 C. The experiments were much more prolonged than those previously carried out in man. Results were compared with simultaneous measurements in the aortic arch, right ventricle, gastrointestinal tract, and bronchial tree. There was no significant difference between alveolar capillary temperatures and those in the right and left heart and bronchial wedge position, even when body temperature was changing. Deep rectal temperatures gave a reasonable estimate of alveolar temperature provided the body temperature was steady, but esophageal and gastric measurements were not reliable, the reading increasing as the stomach was approached. The results support the validity of the helium-argon method and indicate that accurate estimates of alveolar capillary temperature may be obtained by direct measurements in the central circulation or bronchial wedge position.

Note:

With the Technical Assistance of Judith Laurie

alveolar gas exchange; intravascular temperatures; inert gases; solubility of gases; esophageal temperature; gastric temperature

Submitted on December 16, 1963

MEASUREMENT OF BODY TEMPERATURE IN CONSCIOUS SMALL LABORATORY ANIMALS BY MEANS OF AN OESOPHAGEAL THERMOCOUPLE

A device is described for making rapid repeated measurements of body temperature in conscious small laboratory animals. A thermocouple, sealed inside an 18 gauge hypodermic needle is inserted into the oesophagus and the temperature read directly on a calibrated meter.

A SEX DIFFERENCE IN THE TEMPERATURE RESPONSE OF RATS TO EXERCISE

The changes of colonic and tail skin temperatures were measured in male and female rats exercised on a motor-driven treadmill at a speed of 4.6 m/minute. The pattern of changes in these temperatures was the same in the two sexes except that the females tolerated a significantly higher colonic temperature than the males before beginning to vasodilate in the tail, and, perhaps as a result, the females regulated core temperature at a significantly higher level as exercise continued. Ovariectomy or prolonged (7–14 days) treatment with progesterone (12 mg/day) resulted in the temperature response to exercise of the female approaching that of the male, but not entirely eliminating the difference.

PHYSIOLOGICAL REACTIONS TO HEAT OF BUSHMEN AND OF UNACCLIMATIZED AND ACCLIMATIZED BANTU

Bushmen in the Kalahari desert fulfill two criteria for acclimatization to heat. They exercise actively, in hunting, in relatively severe heat in midsummer. Compared with unacclimatized Bantu they have higher sweat rates per square meter and lower heart rates. However, rectal temperatures are not much lower than those of unacclimatized Bantu. River Bushmen present a paradoxical picture. In summer sweat rates are higher than in winter, but are not as high as desert Bushmen. Summer heart rates are, however, higher than in winter. Rectal temperatures in the two seasons are similar. The higher sweat rates in summer are good evidence of better acclimatization than in winter; the higher heart rates may be a reflection of differences in physical fitness in the two seasons.

association of morphology and metabolism on cold exposure; cold responses of Bantu, Bushmen, and Caucasians; heat conductance and skinfold thickness in cold; metabolisms of Bantu, Bushmen, and Caucasians in cold; toe, finger, and rectal temperatures of different ethnic groups in cold

Submitted on February 4, 1964