OPTIMAL FREEZING CONDITIONS FOR CEREBRAL METABOLITES IN RATS
| Autor: | U. Pontén, L. G. Salford, R. A. Ratcheson, Bo K. Siesjö |
|---|---|
| Rok vydání: | 1973 |
| Předmět: |
Male
medicine.medical_specialty Time Factors Phosphocreatine Metabolite Blood Pressure In Vitro Techniques Biochemistry Cellular and Molecular Neuroscience chemistry.chemical_compound Adenosine Triphosphate Oxygen Consumption Internal medicine Cortex (anatomy) Freezing Methods medicine Animals Anesthesia Carbon Radioisotopes Pyruvates Brain Chemistry Cerebral Cortex Brain Oxygenation Carbon Dioxide Hypoxia (medical) Liquid nitrogen Adenosine Monophosphate Rats Adenosine Diphosphate Glucose Endocrinology medicine.anatomical_structure chemistry Cerebral cortex Cerebrovascular Circulation Phenobarbital Lactates Breathing Ketoglutaric Acids medicine.symptom Autolysis |
| Zdroj: | Journal of Neurochemistry. 21:1127-1138 |
| ISSN: | 1471-4159 0022-3042 |
| DOI: | 10.1111/j.1471-4159.1973.tb07567.x |
| Popis: | — Optimal freezing conditions for metabolites were evaluated in 250-450 g rats. As a standard procedure, the brains were frozen in such a way that the blood pressure and arterial oxygenation were upheld during the freezing. The progression of the freezing front was determined by means of implanted thermocouples, and the interruption of the circulation by means of injections of carbon particles into the blood stream. The freezing gave rise to a rapid interruption of the circulation in the superficial cortical layer first reached by the freezing front well before the temperature reached 0°C. In deeper regions the progression of the freezing front was slower and interruption of the circulation occurred simultaneously with the freezing of the tissue. Measurements of labile cerebral metabolites, including phosphocreatine, ATP, ADP, AMP and lactate, failed to show signs of autolysis in the part of cortex which became unperfused at temperatures above zero. Since the energy state was identical in superficial cortical areas and in areas that did not freeze until after 40–90 s, it is concluded that the freezing technique gives optimal conditions for metabolites also in deep cerebral structures. Decapitation of unanaesthetized animals gave rise to large autolytic changes in the cerebral cortex. In unanaesthetized animals that were immersed in liquid nitrogen the changes were less marked and mainly affected the concentrations of phosphocreatine, ADP and lactate. When paralysed animals that were anaesthetized with N2O were immersed in liquid nitrogen the only significant change from the control was a decrease in phosphocreatine content. The virtual absence of autolytic changes in this group of animals was not related to the anaesthesia since more pronounced changes were observed in phenobarbitone-anaesthetized rats immersed in the coolant. These differences could be explained by the fact that spontaneously breathing animals immersed in liquid nitrogen developed arterial hypoxia much faster than paralysed animals. It is concluded that an optimal metabolite pattern can only be obtained in anaesthetized animals, frozen with a method that was described by Kerr almost 40 years ago (Kerr, 1935). If unanaesthetized animals must be used, greater attention should be paid to the oxygenation of the blood during the freezing than to such factors as speed of freezing or depth of anaesthesia. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Plný text