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Biomedical subjects

F Rossberg

Publications and source records attributed to F Rossberg.

At least 19 recordsLinked to original sources
PubMed1992

Heart rate and arterial pressure variability in humans during different orthostatic load.

The influence of posture on the rhythms in blood pressure, heart rate and respiration was tested by means of spectral analysis in 14 healthy subjects. During squatting, standing and sitting, the finger blood pressure was recorded by the non-invasive Penáz technique together with cardiac intervals and respiratory movements. The power spectra obtained from five-minute samples showed that the respiratory components of cardiac interval and pulse pressure were reduced significantly in standing. Compared to squatting, a significant increase of total power in the medium frequency band (0.05-0.15 Hz) for cardiac interval, diastolic and mean pressure could be detected.

Adult↗
PubMed1989

[The current status of noninvasive blood pressure measurement technics].

Methods of measuring the blood pressure by means of cuffs using pressure which changes slowly with respect to intravascular pressure were described in a review. After a short note on methods of deriving the mean pressure from the pulse wave velocity, the principle of unloaded vascular wall and the Penaz technique using this principle was presented in some detail. The method which seems to be of practical relevance, has been elaborated for clinical use in the last years.

Blood Pressure Monitors↗
PubMed1988

[The dynamics of orthostatic cardiovascular immediate and late regulation in healthy adolescents in relation to changed position].

In 16 subjects without any cardiovascular disease the early and the late orthostatic response was tested using the non-invasive continuous blood pressure measurement according to the Penaz principle. The beat to beat analysis of blood pressure revealed an instantaneous blood pressure decrease with standing up from sitting and from squatting; the initial heart rate maximum was markedly delayed against the minimum of mean and pulse pressure. The minimum mean pressure in the finger at the level of diaphragm was 57.8 +/- 14.4 mm Hg, a new steady state-pressure after the change of posture was achieved after about 15 s. The power spectra obtained from 5-minutes samples showed that the respiratory components of cardiac intervals, systolic and pulse pressure decreased markedly in standing. Compared to the control a significant increase of the so-called 10-second-rhythm could be detected.

Adolescent↗
PubMed1988

Initial cardiovascular response on change of posture from squatting to standing.

The immediate cardiovascular responses on active change from the squatting (control) to the standing position differ from those obtained in the lying-to-standing manoeuvre. Without exception, the first beat after changing from squatting to standing showed a decrease in systolic, diastolic and mean pressure by 2.0 +/- 1.1 kPa (14.6 +/- 8.3 mm Hg), 1.4 +/- 1.7 kPa (10.6 +/- 12.6 mm Hg) and 1.9 +/- 1.0 kPa (13.9 +/- 7.3 mm Hg), respectively. During the 4th or 5th pulse after standing the pulse pressure was significantly higher than when lying (P less than 0.01). Mean pressure reached a minimum of 7.7 +/- 1.9 kPa (57.8 +/- 14.4 mm Hg) after 7.1 +/- 1.1 s. Thereafter the blood pressure increased to a new level within about 15 s. 11 of 16 subjects demonstrated a biphasic heart rate (HR) response. The maximum HR was reached after 11.0 +/- 2.4 s of standing. In all experiments, the peaks in HR were distinctly delayed after the blood pressure dips. We conclude that an arterial baroreflex could be implicated in the immediate HR increase after a squatting-to-standing manoeuvre. The subsequent time course of the initial HR response, however, might be induced by other mechanisms.

Adolescent↗
PubMed1988

[Age dependence of spontaneous frequencies and intracardial Baindridge-effect of rabbits between the 3rd and 18th day of life].

With continuous perfusion at defined intraluminal pressures isolated right atria from rabbits were examined. Age groups of 3-6, 9-12 and 15-18 days of life were used to measure the chronotropic response to change of atrial pressure over a range of 0.1 to 0.9 kPa (10-90 mm H2O). At transmural pressure of 0.1 kPa (control) the rate of spontaneously beating atria decreased progressively with age over the first three weeks. As compared to the group of 15-18 days, for each intraluminal pressure the atrial rate was significantly higher in the group of 3-6 days. Already 3-6 days after birth the chronotropic self-control mediated by stretch (Bainbridge effect) was present, this response did not vary significantly from that obtained in the group of 15-18 days of life.

Age Factors↗
PubMed1987

Does the arterial baroreflex control the initial heart rate response to standing?

Following a 6 min period of squatting or sitting the early cardiovascular response to standing up was investigated on a beat to beat basis using noninvasive methods in healthy young subjects. After the active transition the arterial pressure fell immediately, the peak of heart rate response was markedly delayed with respect to the minimum in pulse and mean pressure. It is concluded that arterial barore-flexes can participate in the immediate heart rate increase to standing up from the squatting or sitting position whereas the subsequent phase of the initial heart rate response might be induced rather by other mechanisms.

Adult↗
PubMed1986

[Genesis of the initial heart rate course in a tilt table study and its value for the evaluation of autonomic integrity].

With the help of the mathematical modelling is made evident that the course of the heart rate during the orthostatic immediate reaction can quantitatively not satisfactorily be reflected by the exclusive effect of the baroreceptor regulation. In addition to this, the non-reflex regulation of the frequency through the filling pressure of the right atrium - the dynamics of which established by animal experiments is demonstrated - is therefore involved. By means of the pharmacological blocking of the efferent cardiac nerves in six test persons the cooperation of this chronotropic autoregulation in the tilting table experiment is shown. The results render clear that an assessment of the autonomous integrity on the basis of the initial course of the heart rate with rapid changing of the position is only restrictedly possible on account of the nonreflex proportion of the chronotropic response.

Adult↗
PubMed1985

Chronotropic effects of the reversed carboxyl (RC) analogue of acetylcholine (beta-homobetaine methylester) at defined intraluminal pressures on isolated right rabbit atria.

With continuous perfusion at transmural pressures of 0.1 and 0.5 kPa, beta-homobetaine methylester (HBM) decreased the rate of spontaneously beating atria significantly with an ED50 of about 5 X 10(-6) mol/l. The dose-dependent decrease in the atrial rate was stronger at an intraluminal pressure of 0.5 kPa, at this pressure the dose-response curve sloped more steeply. The stretch acceleration of the atrial rate was also significantly inhibited by HBM. In comparison with acetylcholine, the HBM was over 10 times more effective. Atropine blocked the interactions of the HBM with the muscarinic cholinergic receptors of the pacemaker cells.

Acetylcholine↗
PubMed1983

[Transient behaviour of the heart rate in man depending on respiratory cycle during fast tilt].

The initial heart rate response to rapid passive changing of posture was analysed in 43 normal subjects. The tilting (mean tilt time: 1.7 s) was applied during expiration or inspiration. As compared to inspiration, the 70 degrees head-up tilt during expiration resulted in significantly higher values of heart rate increase and longer duration of the "initial complex", i.e. the immediate increase and the following decrease of heart rate to a minimum after tilting. The heart rate response to tilting from erect to supine position was not symmetrical to that during head-up tilt: at first the heart rate increased, about 6 s after the change of body position heart rate decreased suddenly, mostly below the recumbent control value, which was attained again after about 20-30 s. The distinct initial heart rate response to the head-up tilt probably can be explained in part by the hydrostatically caused drop of the mural pressure at the level of carotid artery and the different sensitivity of arterial baroreflex during the respiratory cycle. Other mechanisms, e.g. the participation of chronotropic autoregulation are discussed.

Adolescent↗
PubMed1983

[Effect of verapamil on chronotropic autoregulation in rabbit atria].

With continuous perfusion at defined intraluminal pressures of 0.1 and 0.5 kPa, the effect of the calcium ion antagonist verapamil on the chronotropic autoregulation mediated by stretch was investigated in right atrial preparations. At both intraluminal pressures verapamil at a concentration of 4 X 10(-7) mol/l decreased the atrial rate progressively with increasing duration of verapamil perfusion. Time-dependent the stretch acceleration was also inhibited significantly at 50-72% of the control values. The findings of the present study support the hypothesis of the participation of a calcium current in the origin of stretch-induced chronotropic autoregulation.

Animals↗
PubMed1983

[Chronotropic effects of carnitine derivatives in isolated rabbit atria at defined transmural pressures].

Acetylcarnitine isomers and gamma-betaine methylesters are closely structure-related to cholinergic agonists. With continuous perfusion at defined transmural pressures of 0.1 and 0.5 kPa their effects on the chronotropic autoregulation of isolated spontaneously beating atria were examined in comparison with acetylcholine. Independent of the transmural pressure, the two isomers of acetylcarnitine had no effects on the heart rate up to a concentration of 10(-3) mol/l. Among the carboxylesters of gamma-betaines, the crotonobetaine methylester was up to 100 fold more effective than acetylcholine. Hydrogenation of the double bond decreased the negative chronotropic response 10 times. The L(-)-carnitine-methylester did not influence the spontaneous heart rate up to 3 X 10(-3) mol/l, but the D-isomer inhibited it significantly. Increase of the transmural pressure caused the same level of heart rate in both controls and atria under free betaines. At transmural pressure of 0.5 kPa, in comparison with 0.1 kPa, a significantly greater impairment of heart rate, released by crotonobetaine-methylester, was observed. Atropine blocked the interactions of the gamma-betaine-methylesters with the muscarinic cholinergic receptors of the pacemaker cells.

Animals↗
PubMed1980

[Model studies of chronotropic cardiac autoregulation].

The dynamic response of heart rate to a step change in transmural pressure and sinusoidally varying pressure was investigated. A simple analog model is described simulating these autoregulation of the cardiac rate.

Acetylcholine↗