Kinetics of isometric relaxation in the myocardium of patients with congenital and acquired heart disease

Vs, Markhasin; Kimmel'man, I. Ya.; Tsyvyan, P. B.

doi:10.1007/bf00837440

Cited by 2 publications

(4 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The relaxation index [6] was calculated by dividing the maximal rate of fall of pressure by the maximal pressure developed, and the relaxation constant [5] was calculated by analysis of the dynamics of the whole phase of decline during relaxation. Substances inducing postcontractions, namely isoproterenol and K2PdCI~, were injected into the aorta by means of an infusion pump.…”

Section: Experimental Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Oscillations of diastolic tension as a possible factor in myocardial insufficiency

Vornovitskii¹,

Ignat'eva²,

Новикова³

et al. 1982

Bull Exp Biol Med

View full text Add to dashboard Cite

KEY WORDS:myocardial insufficiency; oscillations of diastolic tension; sarcoplasmic reticulum; myofibrils.Oscillations of diastolic tension, known as "postcontractions" and unaccompanied by action potential development, have been recorded in isolated preparations of the myocardium of warm-blooded animals and man [I, 7, 8, i0]. Oscillations usually arise during overloading of the myocardial cells by Ca 2+ ions [i, i0].It has been suggested that the oscillations arise as a result of recirculation of Ca 2+ ions between the sarcoplasmic reticulum and the myofibrils [i, 7, 8]. The amplitude of the oscillations usually increases in the presence of myocardia I hypertrophy [4,9], combined with a decrease in the ability of the reticulum to take up Ca 2+ [Ii] and by slowing of relaxation [5,6]. However, the question of the link between the appearance of oscillations and slowing of relaxation has not been studied.In the investigation described below this problem was studied in experiments on the isovolumic guinea pig heart.In experiments on the atrial trabeculae of patients with heart diseases the frequency and amplitude of spontaneous oscillations were compared with parameters reflecting the degree of the pathological changes. EXPERIMENTAL METHODIsolated guinea pig hearts were perfused through the aorta with Krebs' solution saturated with carbogen (96% O~ + 4% C02) by means of a peristaltic pump with an output of I0 ml/min/g. A small balloon filled with fluid was introduced into the chamber of the left ventricle through an incision in the wall of the left atrium.The pressure in it was measured by means of a Gould Statham P 23DB transducer. The signal from the transducer, its first derivative, and also the ECG from the subendocardial layer of the apex of the heart were recorded on a Gould Brush 2200 recorder.The relaxation index [6] was calculated by dividing the maximal rate of fall of pressure by the maximal pressure developed, and the relaxation constant [5] was calculated by analysis of the dynamics of the whole phase of decline during relaxation. Substances inducing postcontractions, namely isoproterenol and K2PdCI~, were injected into the aorta by means of an infusion pump.Altogether 25 preparations of the auricles of the right atrium from patients with rheumatic and congenital heart diseases were investigated [2]. Trabeculae 3-5 mm long and not more than 1 mm thick were isolated from the auricle.The trabeculae were placed in a working chamber through which flowed Tyrode solution saturated with carbogen at 32-34~One end of the trabecula was attached to a stationary rod fixed to the floor of the chamber, the other end was attached to the rod of a 6MKhlS mechanotron.The preparation was stretched by a load of 200-500 mg and stimulated by square pulses of above threshold strength, with a frequency of 0.5 Hz and a duration of 10-20 msec.The signal from the output of the mechanotron was led to the input of an SI-18 oscilloscope or Mingograph-81 instrument. EXPERIMENTAL RESULTSPostcontractions of the heart during hypothermi...

show abstract

Section: Experimental Methodsmentioning

confidence: 99%

“…The amplitude of the oscillations usually increases in the presence of myocardia I hypertrophy [4,9], combined with a decrease in the ability of the reticulum to take up Ca 2+ [Ii] and by slowing of relaxation [5,6]. However, the question of the link between the appearance of oscillations and slowing of relaxation has not been studied.…”

Section: Introductionmentioning

confidence: 99%

Oscillations of diastolic tension as a possible factor in myocardial insufficiency

Vornovitskii¹,

Ignat'eva²,

Новикова³

et al. 1982

Bull Exp Biol Med

View full text Add to dashboard Cite

show abstract

“…They used segments of atrial auricle and, occasionally, of LV from patients with congenital or acquired heart disease. Recording the mechanical activity of explanted tissue, using custom-made micro-mechanographic equipment, they found that preparations from failing heart developed significantly lower peak tension than normal myocardium, and that the time-course of contraction and relaxation were significantly slower ( Grigorian et al., 1983 , Markhasin and Tsivjan, 1980 , Markhasin et al., 1981 ). Cellular AP, simultaneously recorded from several (25–70) cells of each preparation using floating microelectrodes, allowed the authors to assess variability in AP characteristics in the tissue.…”

Section: Section 1: Cellular Heterogeneity In Human Heartmentioning

confidence: 99%

“…Cellular AP, simultaneously recorded from several (25–70) cells of each preparation using floating microelectrodes, allowed the authors to assess variability in AP characteristics in the tissue. They observed less negative resting potentials (RP) in preparations from failing heart ( Markhasin et al., 1981 , Tsyv'ian and Markhasin, 1981 ). RP levels varied between cells from the same preparation by about 20%, independent of the disease.…”

Section: Section 1: Cellular Heterogeneity In Human Heartmentioning

confidence: 99%