Metabolic effects of somatotropin in rats acclimated to adverse environments

¹ Physiology-Biophysics Branch, School of Aviation Medicine USAF Aerospace Medical Center, Brooks Air Force Base; and Psychiatric and Psychosomatic Research Laboratory, Veterans Administration Hospital; and Baylor University College of Medicine, Houston, Texas

Effects of somatotropin (STH, growth hormone) in low dosage on metabolic functions were determined in adult male rats acclimated to hot, neutral or cold environments or to low barometric pressure. Urinary determinations (24-hour, fasting) provided the means for evaluating nitrogen and mineral metabolism. The interplay between STH and environmental factors thus received some clarification. STH had certain effects in normal rats which were clearly heat- or altitude-mimetic. In combination, STH and heat had synergistic effects on urea, phosphate and the calcium/phosphorus ratio; and STH and altitude acted synergistically on phosphate and the sodium/potassium and calcium/phosphorus ratios. STH and cold had antagonistic effects on urea, uric acid and the uric acid/creatinine ratio, but synergism was evident in the sodium/potassium ratio. The effects of STH during the initial stage of recovery from heat, altitude or cold were also studied. While some of the recovery reactions were augmented by STH, others were blocked or at least diminished, and there were instances where STH had normalizing effects.