Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1965-1969  (4)
Collection
Publisher
Years
Year
  • 1
    ISSN: 1432-2013
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary As has been previously shown, non-shivering thermogenesis is the prevailing mechanism of heat production in the newborn guinea pig exposed to a cool environment. In the course of the first two to three weeks of life, non-shivering thermogenesis is reduced and replaced by shivering. In the present study this process has been shown to be linked with morphological and functional alterations in the multilocular adipose tissue. The functional changes have been evidenced by the following experiments: In two groups of guinea pigs, 0–2, and 25 to 42 days of age, respectively, the local temperature and blood flow were measured in the large fat pad located between the scapulae, in addition to gaseous metabolism, electrical activity of the sceletal musculature and colon temperature. In the young animals the rise of O2-consumption as occuring on cold exposure was accompanied by a temperature rise in the fat tissue (absolute and relative to the colon temperature), whereas electrical activity of the musculature remained low. Blood flow of the fat tissue increased at the same time. In the older animals, the temperature difference between the fat tissue and colon remained low but it occurred shivering. The increase of temperature difference and blood flow was reduced or abolished in the young animals by Alderlin, an adrenergic β-receptor blocking agent that has been previously shown to block non-shivering thermogenesis; on the other hand, the blockade of non-shivering thermogenesis caused an onset of shivering. Further, noradrenaline and adrenaline have been shown to increase blood flow of the fat tissue in the young animals. The results indicate. 1. that the brown adipose tissue can be considered an important site of non-shivering thermogenesis in the newborn guinea pig, and 2. that the thermogenic capacity of the brown fat is diminished with increasing age.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-2013
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei Meerschweinchen im Alter von 0 Tagen bis durchschnittlich 11 Monaten wurde die Altersabhängigkeit des maximalen Ausmaßes der zitterfreien Thermogenese mit folgenden Methoden bestimmt: 1. Mit dem Noradrenalintest, das ist Bestimmung der O2-Aufnahmesteigerung nach Noradrenalininjektion, 2. mit dem „Blockadetest“, d.h. durch quantitative Erfassung der Beziehung zwischen elektrischer Muskelaktivität und O2-Aufnahme vor und nach Blockade der zitterfreien Thermogenese mit einem β-Receptorenblocker. Die zitterfreie Thermogenese betrug beim neugeborenen Meerschweinchen rund 250% des Grundumsatzes. Bei Aufzucht in warmer Umgebung nahm sie im Verlauf von 4 Wochen bis auf 10 bis 15% ab. Bei Aufzucht in kalter Umgebung (+3° C) bzw. vierwöchiger Adaptation an + 3° C nach vorheriger Aufzucht in wärmerer Umgebung betrug die zitterfreie Thermogenese im Alter von 3 Monaten noch ca. 60%, im Alter von 9 Monaten nur noch 40% des Grundumsatzes. Bei tieferer Adaptationstemperatur, wurden keine höheren, sondern sogar geringere Werte erhalten. Der Abbau der zitterfreien Thermogenese war von einem Schwund an braunem Fettgewebe begleitet.
    Notes: Summary In guinea pigs, 0 days to, on the average, 11 months of age, the age-dependency was determined of the maximum extent of non-shivering thermogenesis, using the following methods: 1. The noradrenaline-test: measurement of the increase in oxygen uptake on a noradrenaline injection. 2. The “blocking test”: quantitative evaluation of the relationship between electrical activity of the musculature and oxygen uptake before and after blockade of non-shivering thermogenesis by a β-receptor blocking agent. In the newborn guinea pig non-shivering thermogenesis amounted to 250% of the basal metabolic rate. It decreased to 10–15% within four weeks in animals which were reared in a warm environment. In animals reared in the cold or adapted to a cold environment (+3° C) after having been reared in a warm environment the non-shivering thermogenesis amounted to about 60% at the age of 3 months and to no more than 40% at the age of 9 months. With lower adaptation temperatures no larger but smaller amounts of non-shivering thermogenesis were obtained. The loss of non-shivering thermogenesis was accompanied by a reduction of the brown adipose tissue.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 282 (1965), S. 362-375 
    ISSN: 1432-2013
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electromyographic and metabolic studies in unanesthetized newborn guinea pigs have shown that, during the very first days of life, electrical activity of the musculature remains at zero level, or is only slightly increased, when the animals are exposed to a cold environment (8 and 16°C), although oxygen consumption rises by 200 to 300% over basal rate under such conditions. The oxygen consumption measured at an ambient temperature of 8° C amounted to 70 ml/kg min, on the average, and this amount was sufficient to maintain the colon temperature of the small young animals at adult level. In point of this prevalence of non-shivering thermogenesis temperature regulation of the newborn guinea pig resembles that of cold adapted adult subjects. Older animals displayed visible shivering, and rhythmic discharges could be recorded from the musculature under the same temperature conditions. Even with vigorous shivering, however, oxygen uptake in animals 2 to 3 weeks of age did not exceed 45 ml/kg min, and the colon temperature was kept at a level that was lower than in young newborn animals. This demonstrates that non-shivering thermogenesis is reduced with increasing age and that the shivering mechanism is less effective. The large heat production that is required to maintain a constant body temperature in small newborn animals can only be provided by the more effective chemical thermogenesis the presence of which can thus be considered an adjustment to the small body size of the neonate.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...