Application of high hydrostatic pressure as a cryoprotective was evaluated for the bovine sperm cell, kidney tissue, and the whole kidney. Spermatozoa samples were pressurized between 172 and 1724 bar for various lengths of time. The effect of pressure and cooling at 5 °C/min, 35 °C/min, and 55 °C/min to −60 °C was investigated. Application of pressure to sperm cells resulted in extensive damage, as shown by a decrease in motility, an increase in morphological a bnormalities, and the release of enzymes. Freezing of sperm cells, kidney tissue, and the whole kidney under high pressure was significantly more damaging than freezing at the same rates at atmospheric pressure. Pressure did not act as a cryoprotective agent but instead led to gross cellular damage, either when applied at 4 °C or during freeze-thaw procedures.
LDH and GOT can be used with assurance as indicators of pressure-temperature effects in most regions of interest, specifically below 20,000 psi. LDH was susceptible to pressure deactivation at pressure levels below those tolerated by chymotrypsin, trypsin and alpha-amylase of Bacillus subtilis (17, 18, 20). Samples of LDH and GOT cooled to −20 °C were deactivated to the greatest extent by the application of pressure. The presence of glycerine and DMSO appeared to increase the sensitivity of GOT and LDH to pressure deactivation. When pressure was applied before cooling all pressures above 15,000 psi resulted in some deactivation of LDH and all pressures above 20,000 psi resulted in some deactivation of GOT.
LDH and GOT can be used with assurance as indicators of pressure-temperature effects in most regions of interest, specifically below 20,000 psi. LDH was susceptible to pressure deactivation at pressure levels below those tolerated by chymotrypsin, trypsin and alpha-amylase of Bacillus subtilis (17, 18, 20). Samples of LDH and GOT cooled to −20 °C were deactivated to the greatest extent by the application of pressure. The presence of glycerine and DMSO appeared to increase the sensitivity of GOT and LDH to pressure deactivation. When pressure was applied before cooling all pressures above 15,000 psi resulted in some deactivation of LDH and all pressures above 20,000 psi resulted in some deactivation of GOT.
This automatic system for controlling the temperature of biological materials is designed to allow the selection of cooling rates, freezing rates, storage temperatures, and warming and thawing rates. These programs are easily obtained by drawing a suitable time-temperature curve on a plastic-coated card. The control device follows the line drawn on the card and regulates the flow of the refrigerani, liquid nitrogen. This automatic control system has been used to control liquid bath temperatures, to control set point storage refrigerators, with a heat exchanger to control the temperature of a moving fluid, and to control a variable rate freezer. Biological materials have been frozen, stored, and thawed automatically.
