Endocrine and messenger systems during adaptation to high-altitude conditions

Of endocrine cascades and messenger systems, the authors con­ducted this study involving two series of experiments. The pattern of interaction of hormones and secondary messengers while adapting to high-altitude was clarified in the first series. The re­sponse of phosphoinositide to exogenous epinephrine was exam­ined in the second series. The experimental data are represented as primary mean values ± standard deviations. Two phases of activity of the hormonal system are shown. These are the exci­tation of the hypothalamopituitary cascade and the enhanced production of glucocorticoids and catecholamines during early adaptation and the return of activity of the hormonal system to the baseline values by day 14 of adaptation. By that time the re­arrangements in the phosphoinositide messenger system consists in increasing the proportion of polyphosphoinositides in the total membranous fraction of inositol-containing phospholipids, in adrenalectomized animals to a greater extent. The above events give rise to new coordination relations between hormones and secondary messengers. It is concluded that that the phosphoi­nositide messenger system is involved in the formation of defense mechanisms the reduce the destructive effects of large amounts of epinephrine.