[The use of pharmacological agents for the increase of +Gz tolerance in macaca mulatta].

Tolerance of rhesus monkeys to increased +Gz loads was studied in relation to the conditions of the blood circulation functioning. In four anaesthetised monkeys, the external carotid arteries were ligated and a biomedical cuff was implanted on the common carotid arteries to measure blood pressure, linear blood velocity, and to register EKG. Blood flow in the carotid artery nearing the zero served as the criterion for termination of rotation with a gradient of 0.01 units/s Each animal was centrifuged 4 times at a week interval: first when intact and then after injection of m-cholinolytic metacine, adrenomimetic metazone and or reopolyglucin which increases the plasma volume. These studies demonstrated that the reflex effect on the heart (elevated CO and increased arterial pressure as a result of moderate tachicardia conditioned by metacine) or vessels (activation of alfa-receptors by metazone) as well as an increase in the volume of intravascular fluids, are almost equally favourable to the maintenance of the central blood volume, and the +Gz-tolerance, i.e. about 35% (delta = 1.62-1.77 units).