Phases of the primary response of the sympathoadrenal system to stress

Abstract

A state of stress was produced experimentally in 42 sexually mature mongrel dogs (males) under i0 kg in weight, by one-stage trauma to the soft tissues of the thigh, below the threshold for inducing shock, inflicted by means of a percussive mechanism (Efficiency Suggestion No. 850, 1984, Rostov Medical Institute), whereby the intensity of nociceptive action could be regulated so as not to exceed the threshold of behavioral response (Instructions of the Ministry of Health of the USSR specifying the rules of work with experimental animals). The dogs were killed by one-stage decapitation in the control (intact animals, group i), and also I015 sec (group 2) and 60 sec (group 3) after exposure to stress, under pentobarbital anesthesia (10-15 mg/kg body weight). Tissue samples were placed in ice, quickly separated, and processed. Adrenalin (A), noradrenalin (NA), dopamine (DA), dopa, and free forms of metanephrine (MN) and normetanephrine (NMN) in the blood and tissues of various organs were determined fluorometrically [6, 7]. The intensity of fluorescence was measured by means of an Hitachi spectrofluorometer (Japan). Monoamine oxidase (MAO) activity in the blood and tissues was determined by the method [2] and expressed in micrograms of ammonia per milligram protein. The protein concentration was measured as in [13]. To estimate qualitative changes in CA metabolism the values of the coefficients of correlation between concentrations of their fractions were calculated by the method in [i].