[The hypothalamic mechanisms of the development of arterial hypertension in old age].

The electrical activity of hypothalamic nuclei was found to change in accordance with changes in arterial blood pressure in old rabbits with reflexogenic hypertension. Stimulation of the hypothalamus induced an obvious increase in the blood pressure, considerable changes in cardiac activity, coronary insufficiency occurrence and alteration of the myocardium structure. An increase in excitability of the pressor structures of the anterior and posterior hypothalamic areas occurred with ageing.

[Regulation of corticoliberin and corticotropin incretion in old age].

Experiments on adult and old rats have shown age-related decrease of the CRF incretion in the hypothalamus, weakening of its response to dexamethasone, as well as a decrease of receptor corticosterone binding. Against this background in the hypophysis of old rats sensitivity ox CRF and serotonin increased, in stress the same content of ACTH as in adult rats secreted, it more markedly reacted to dexamethasone, and receptor of corticosterone binding increased in hypophysis. In old age, the role of hypophyseal link in control of the adrenocortical function is assumed to increase in stress.

[The system of regulation of aldosterone secretion in old rats].

The experiments performed on mature (4-6) and old (28-30 months) rats revealed changes developed in old animals in various links of regulatory system of aldosterone secretion: the decreased hypothalamohypophyseal control of mineralocorticoid secretion, increased sensitivity of glomerular zone to ACTH, vasopressin, K+ and of myocardium skeletal muscle and renal tissue to aldosterone. Changes in tissue sensitivity to aldosterone may be conditioned by the increased affinity of mineralocorticoid receptors to aldosterone in old age.