Testicular growth and functional capability after 4-24 weeks of continuous exposure to 11 ATA He-O2.

A study of testicular developmental and functional capabilities was made of rats continuously exposed for 4, 8, 12, 16, 20, or 24 weeks to 1 ATA He-O2, 11 ATA He-O2, or ambient pressure air environmental conditions. Other groups of rats were exposed for 24 sequential weeks to the same three sets of environmental conditions with brief interruptions for decompression and recompression at the end of each 4 weeks. The rats were comfortably housed and adequately fed in accord with earlier investigations. Visual observations of the testes at the time of slaughter, dry matter content of the testes, and histological examinations--all revealed normal growth and active spermatid formation from healthy germinal epithelia in all semeniferous tubules. The stress of hyperbaria or of helium to 11 ATA did not inhibit or destroy male germinal epithelial functional capabilities.

Vitamins limiting for growth of subjects fed a normal diet under hyperbaric He-O2 conditions.

A growth study was conducted of rats continuously exposed for 4 weeks to ambient air, 1 ATA He-O2, or 11 ATA He-O2 conditions and fed one of 16 diets. The diets were the standard diet alone (adequate according to National Research Council standards); the standard diet with additional casein (50%), fat (25%), and all vitamins (25%); or the standard diet with all vitamins (25%), or all vitamins increased (25%) except one, which was supplied at the standard level. The standard diet was inadequate to support a normal rate of growth when fed under 11 ATA He-O2 conditions. Supplemental casein, fat, and vitamins or all vitamins alone adequately provided nutrients necessary for a normal rate of growth by hyperbaric exposed rats. The standard levels of thiamine, pantothenic acid, biotin, and vitamin K were inadequate and the standard levels of niacin, and vitamins A, D, and E were marginal in supporting growth when fed under hyperbaric conditions.

Dietary requirements of subjects exposed to hyperbaric He-O2 conditions: effects of various levels of vitamin supplementation.

A 24-d growth study was conducted on rats exposed to ambient air, 11 ATA He-O2, or 21 ATA He-O2 conditions. The rats were fed either a standard diet or the standard diet supplemented with 25, 50, or 100% increase of all vitamins, or the last with an additional 50 or 100% increase of casein. Fat, as cod liver oil was increased 0.5, 1.0, or 2.0% of the diet as the vitamins were increased. The vitamin and fat-supplemented diets, with or without supplemental casein, were adequate to support normal growth of the rats exposed to 11 ATA but not 21 ATA He-O2 conditions. Urine excretion and water consumption were closely related and varied in accordance with the adequacy of the diet. Feed digestibility was not a limiting factor in determining the growth of the rats under the three environments. The composition of the rat carcasses varied minimally.

Dietary requirements of subjects exposed to hyperbaric He-O2 conditions: effects of supplementation with major nutrient groups.

A 4-week growth study was conducted to determine whether changes in the type of diet could adequately compensate for the increased demands made upon the body by the stresses associated with exposure to hyperbaric He-O2 conditions. A normal rat diet (Hegsted-Chang) was used as a standard diet. This diet was also modified by increasing the fat content 25%, mineral mixture 25%, casein 50%, or all vitamins (including cod liver oil) 50%, or by decreasing the casein portion 10% from the standard levels. The corn starch portion was adjusted appropriately to maintain isocaloric properties of the various test diets. Male Sprague-Dawley rats served as the experimental subjects and were exposed to 1 ATA room air, 11 ATA He-O2, or 21 ATA He-O2 environmental conditions. The rats fed fat-supplemented diets grew as well under 11 ATA He-O2--but not under 21 ATA He-O2 conditions--as those fed the standard diet and exposed to 1 ATA room-air conditions. The rats fed protein-supplemented diets grew as well under both hyperbaric conditions as the control rats. Although the rat growth under the hyperbaric conditions equaled that under control conditions, it was less efficient because more food was required to produce each 1 g of gain. Significant differences were also observed in the apparent digestibilities of the various diets and in the protein, fat, and mineral contents of the carcasses.