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R Mohnhaupt

Publications and source records attributed to R Mohnhaupt.

36 records · Page 2Linked to original sources
PubMed1976

[Observation in 10 calves with a survival time of more than 100 hours after total heart replacement (author's transl)].

It is reported on 10 calves surviving total artificial heart replacement more than 100 hours. Pneumatically driven double-chambered blood pumps made of silastic were implanted. During the experiments an increase of the right atrial pressure as well as a rise of the perfusion volumes (CO) and of the blood volumes could be found regularly. At autopsy congestion of the organs especially of the liver was a regular finding. The changed hemodynamic is first seen as possible reason for this developments. The influence of anemia and the possible disturbances in the neurohumoral autoregulation of the animals by unphysiologic pressure curves are discussed.

Animals↗
PubMed1976

New methods for the in vitro investigations of the flow patterns in artificial hearts.

With the 3 applied methods one can investigate and obtain most of the interesting aspects of the flow within blood pumps: an integral picture of the flow, the development and position of stagnation flow, the time course of the velocity in points of special interest, the turbulence, and an integral picture of the mean boundary layer flow. The measurements have shown that the flow in the blood pumps is turbulent, the turbulence can be considered harmless, because its intensity is much weaker than that of a valve; there is a correspondence between the hotfilm method and the dye-washout method, and that there is a correspondence between the dye-washout method and the in vivo clot formation. Pumps, which have been designed according to these measurements, have been implanted in a series of calves. The pumps now have a smooth continuous inner surface and usually show no thrombus formation at all (anticoagulants are used) at the postmortem. Some animals do very well, such as the one in Figure 16 during his daily walk of 500 M on the treadmill. The animal is in its 45th day of survival and remains well to date.

Animals↗
PubMedDate not supplied

Acute effects of angiotensin II on renal haemodynamics and excretion in conscious dogs.

The effects of a 60-min intravenous infusion of angiotensin II (A II; 4 or 20 ng A II/min/kg body weight) on renal blood flow (RBF; electromagnetic flow transducer, control value 19-25 ml/min/kg), glomerular filtration rate (GFR; control value 4.2-5.0 ml/min/kg), mean arterial blood pressure, sodium excretion, water excretion, and plasma A II and plasma aldosterone concentrations were examined in 6 chronically instrumented female conscious beagle dogs kept on three different dietary sodium intakes (SI): SI 0.5 or SI 2.5 mmol Na/kg/day or SI 4.5 mmol Na/kg/day plus an oral saline load prior to the experiment SI 4.5(+) dogs. Four nanograms A II decreased RBF and GFR in SI 4.5(+) dogs without changing the filtration fraction (FF%); in SI 0.5 dogs the RBF decreased, and the FF% increased. Twenty nanograms A II decreased RBF and increased FF% in all dietary protocols, less in SI 4.5(+) dogs. The mean arterial blood pressure increased in all dietary protocols by 10-15 mm Hg (4 ng A II) and 32-37 mm Hg (20 ng A II). Sodium and water excretions decreased by 32 and 46%, respectively, in SI 4.5(+) dogs at both doses of A II. The plasma aldosterone concentration increased in all but one protocol: 4 ng A II, SI 4.5(+) dogs. It is concluded that when A II plasma concentrations are most likely borderline to pathophysiological conditions (up to an average of 370 pg/ml), the GFR is less decreased than the RBF. This phenomenon also can be observed at lower plasma A II concentrations (average 200 pg/ml), when the renin-angiotensin system had been previously moderately activated.

Aldosterone↗
PubMedDate not supplied

Influence of captopril on 24-hour balances and the diurnal patterns of urinary output, blood pressure, aldosterone and atrial natriuretic peptide in conscious dogs.

The diurnal time course of urinary flow rate (UV), urinary sodium (UNaV), and potassium (UKV) excretion, and of hormones such as atrial natriuretic peptide (ANP) and aldosterone, was investigated during 5 days of continuous captopril infusion (15 micrograms.kg body weight-1.min-1) in 4 conscious dogs on a high sodium diet (14.5 mmol Na.kg body weight-1.24 h-1). All food and water was given once daily at 8.30 a.m. On the control day and on days 1, 3, and 5 of captopril infusion, urine was collected by an automated system at 20-min intervals over 24 h, blood was taken every 4 h. Mean arterial blood pressure (MABP) and heart rate were evaluated as 5-min averages. Time courses of UNaV, UV, and UKV were compared with the individual control day without captopril. With captopril, 24-hour balances for Na and H2O were slightly negative, while the K balance was slightly positive for 2-3 days. Thereafter, all 24-hour balances were restored. MABP continued to decrease even after Na and water intake and output had come into balance again. Captopril treatment changed the diurnal excretion pattern for UNaV and UV characteristically. In the postprandial period until 5 p.m., less Na and urine were excreted than on the control day, whereas during the evening and night more Na and urine were excreted. The changes in the excretion pattern persisted for the entire observation period. The results indicate that disturbances in the regulating systems, induced by converting-enzyme blockade, bring about complex reactions of, e.g., MABP, ANP and aldosterone that finally restore Na and water 24-hour input/output balances.

Aldosterone↗