X-Message-Number: 2254 From: Subject: CRYONICS: Audrey Smith's Frozen Rats Date: Sat, 15 May 93 21:35:04 PDT While doing research for my independent project, I found some interesting articles in Audrey Smith's _Biological Effects of Freezing and Supercooling_ I thought you may find them interesting. If anyone knows of more recent studies which contain similar results, please let me know. "We found, in collaboration with animal psychologists, that rats which had been trained to solve problems of finding food in mazes showed no appreciable loss of memory after cooling to a body temperature just above the freezing point (Andjus, Knopfelmacher, Russell and Smith, 1955 and 1956). The heads of the animals were packed in ice and there was no possibility that the brain could have remained warmer than the colon. Activity of the cerebral cortex, as judged by electro encephalograms, ceases at about +18.degree C in the rat, so that cerebral activity must have been arrested for 1-2 hr. in all the animals tested. After reanimation they were nevertheless, capable of acting on previous experience. This result was not consistent with the theory that memory depends upon a continuous passage of nerve impulses through actively metabolizing neurones in the brain (Andjus, Knopfelmacher, Russell and Smith, 1955 and 1956). Although behaviour and general health returned to normal soon after reanimation from 0.degree C, fertility and sex drive were lost for about 2-4 weeks and reduced until about 8 weeks after male and female rats had been cooled to 0.degree C and reanimated for the first time (Goldzveig and Smith 1956a)." (quoted from Smith, Audrey; _Biological Effects of Freezing and Supercooling_, The Williams and Wilkins Company: Baltimore, 1961, pp 316-317) Dr. Smith also appears to have recognized the use of low temperatures for long term storage/revivification of mammals. "So far no technique has been evolved for perfusing individual organs or the whole mammal with glycerol and removing it without damage. If this could be done it might be possible to cool the intact mamal to and resuscitate it from temperatures as low as -70.degree C. Long term storage of frozen mammals might then be considered. It must be emphasized that there is no prospect of accomplishing this in the near future."(quoted from Smith, Audrey; _Biological Effects of Freezing and Supercooling_, The Williams and Wilkins Company: Baltimore, 1961, p 363) She also describes experiments that were done on the viability of nerve tissue. Decapsulated rat ganglia together with their unsheathed nerves which had been treated with 15 per cent glycerol in Krebs' solution and cooled slowly to -79.degree C recovered after thawing. In the first of the two cooling methods referred to in the quote, the cells were cooled in liquid glycerol medium; in the second method, the cells were immersed in glycerol solution, then frozen in open air on a glass dumb-bell. "Storage at -76.degree for 24 hr. had little harmful effect on ganglia which had been cooled in the presence of 15 per cent glycerol by either of the two slower [cooling] methods. The action potentials recorded from the pre- and post-ganglionic nerves and the action potentials which had been transmitted through the ganglion were unaltered in amplitude and duration. There was no impairment of the capacity to transmit a rapid succession of impulses across the ganglionic synapses. Preparations which had been kept at -76.degree C for longer than 1 day did not, however, recover completely as judged by diminution of the electrical responses; action potentials of reduced amplitude were obtained from a preparation which had been kept for 21 days at -76.degree C (Pascoe, 1957)"(quoted from Smith, Audrey; _Biological Effects of Freezing and Supercooling_, The Williams and Wilkins Company: Baltimore, 1961, p 239) Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=2254