New parameters in quantitative structure-activity relationships

Translated from Khimiko-farmatsevticheskii Zhurnal, Vol. 28, No. 10, pp. 53–56, October, 1994.     

Cardiovascular effects of the calcium sensitizer, levosimendan, in heart failure induced by rapid pacing in the presence of aortic constriction.

1. The haemodynamic effects of a novel cardiotonic drug, levosimendan, which has both calcium-sensitizing and phosphodiesterase III (PDE III) inhibitory properties, were studied in conscious dogs in which heart failure had been induced by prolonged cardiac pacing in the presence of aortic constriction. These effects were compared with those in sham-operated dogs with essentially normal cardiac function. 2. Eighteen mongrel dogs were instrumented for the measurement of left ventricular pressure (LVSP, LVEDP) and contractile function (dP/dt; dP/dt/P). In twelve dogs a balloon catheter, positioned in the thoracic aorta, was inflated producing an approximate 60% reduction in effective aortic diameter. Twenty min later rapid ventricular pacing (240 beats mean-1) was commenced and maintained for 48 h by means of a bipolar pacing electrode introduced into the right ventricle. This electrode served also for recording changes in the endocardial electrogram in the absence of pacing. Six of these dogs were used to evaluate the haemodynamic changes of pacing-induced heart failure; a further six of these dogs the haemodynamic changes elicited by levosimendan under these conditions. Six sham-operated dogs (group 2) served as controls. 3. In six dogs (group 1) the haemodynamic alterations were assessed after the development of heart failure. In the presence of aortic constriction, 48 h continuous rapid cardiac pacing resulted in a marked deterioration in left ventricular function which remained stable for at least 48 h after cessation of pacing. Thus, there was a marked reduction in LVSP (15%), +dP/dtmax (35%), -dP/dtmax (36%) and also in dP/dt/P (29%), whereas LVEDP was increased considerably (from 6.4 +/- 1.4 to 20.0 +/- 2.2 mmHg).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of synchronization in the pacemaker during high-frequency atrial stimulation

I. M. Sechenov Medical Academy, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. D. Ado.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 111, No. 5, pp. 454–456, May, 1991.     

The effect of increased nitrogen pressure on motor activity and the intercentral relationships of the brain of monkeys

The influence of increased nitrogen pressure up to 19 ata was investigated in chronic experiments on monkeys of a species of Javan macaques (Macaca irus)with electrodes implanted in cortical and subcortical regions of the brain. The phasic character of the changes of motor activity of the animals, an increase in the spectral density of the average power of the EEG in the range of frequencies from 4 to 20 Hz, and a disturbance in the connectedness of the electrogenesis of the reticular formation of the midbrain with the bioelectrical processes in the substantia nigra, the head of the caudate nucleus, and the frontal and motoric areas of the cortex were identified in the course of nitrogen compression at a rate of 1.0 ata per 1 min.Translated from Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 78, No. 3, pp. 26–32, March, 1992.