Participation of the medial reticular formation of the medulla oblongata in the supraspinal control of locomotor and postural activities in the guinea pig.

The influence of microinjections of novocaine (1.5 microliters of a 2% solution) into the ventromedial areas of the reticular formation of the medulla oblongata on the effects of electrical stimulation of the mesencephalic locomotor region, and of adequate stimulation of the vestibular apparatus, was investigated in experiments on decerebrate guinea pigs. It was demonstrated that such injections are accompanied by a reversible increase in the threshold of stimulation of the region indicated, necessary for the initiation of locomotor rhythmicity, as well as by the suppression of vestibular influences on the activity of the flexor muscles of the extremities.

Heart adrenoreactivity during acute haemic hypoxia.

The influence of acute haemic hypoxia of mild and moderate degree, produced by subcutaneous administration of sodium nitrite (25-30 or 50 mg/kg) supporting the blood haemoglobin production, on heart adrenoreactivity was studied in experimental rats. An intensified sympathoadrenal activity was detected, that manifested itself by a marked increase in adrenaline content in the hypothalamus, brain stem and heart. In analogous experiments performed in dogs, with increasing severity of hypoxia a decrease in arterial pressure and left ventricular pressure, increase in left ventricular end-diastolic pressure, and an impairment of myocardial contractile function were observed.

Involvement of endothelium in vasodilating effects of vintoperol.

Experiments were performed on vessels of the femoral vascular bed of anesthetized dogs and on isolated rings of the rat pulmonary artery, vena cava, and thoracic aorta. Vintoperol was administered intra-arterially (0.01, 0.

Functional hyperemia of skeletal muscle: role of endothelium.

The role of the endothelium and endothelium-derived vasoactive factors in the development of skeletal muscle functional hyperemia was studied. Experiments were performed in anesthetized dogs. Functional hyperemia of isometrically contracted gastrocnemius muscle was produced by direct electric stimulation.

Pooling of blood in postischemic shock is modulated by platelet-activating factor (PAF).

In experiments on dogs, i.v. administration of platelet-activating factor (PAF) (500 ng/kg) was shown to induce hypotension which, apart from decreased myocardial contractility, was characterized by blood pooling in veins (82.

On the mechanism of the involvement of endothelium in reactive hyperemia.

Experiments on anesthetized dogs and on vascular test-preparations demonstrated that reactive hyperemia (RH) was accompanied by the appearance of vasodilator in the blood, and that the level increased with the duration of occlusion of the artery. Removal of the endothelium of the part of the vascular bed studied using saponin, decreased the RH and relaxation of a test-preparation. A rise of pressure in the vascular bed, and a decrease in the deformability of the endothelium resulting from pretreatment with dimerized glutaraldehyde, affected both the hyperemia and the reaction of the vascular preparation in a similar way.

Complex sensorimotor choice reaction time in individuals with varied functional motility of nervous processes.

Statistically significant differences of the average values of the length of the latent period of a complex sensorimotor choice reaction (semantic differentiation) were identified in 246 subjects (men, average age 21 years) differing in the level of functional motility (I-IV). The calculation of Pearson correlation coefficients revealed significant negative associations between the indices of functional motility and the lengths of latent periods. It seems possible, on the basis of these data, to consider the length of the latent period of complex semantic choice reactions as an informative indicator of the functional motility of nervous processes.

Receptors for ATP in rat sensory neurones: the structure-function relationship for ligands.

1. The pharmacological properties of the ATP-activated conductance in isolated sensory neurones of the rat were investigated by use of voltage clamp and concentration clamp techniques. 2.