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Biomedical subjects

H Schad

Publications and source records attributed to H Schad.

At least 55 records · Page 3Linked to original sources
PubMed1986

[Effect of ganglionic blockade and subsequent i.v. infusion of catecholamines and angiotensin II on the formation and transport of lymph. Studies in anesthesized dogs and a review of the literature].

The effect of ganglionic blockade (GB) and subsequent i.v. infusion of adrenaline (AD), noradrenaline (NA), isoproterenol (IP), and angiotensin II (AII) on thoracic duct lymph flow (LF) and transcapillary escape rate of plasma proteins (FER) was studied in anaesthetized (Nembutal), paralyzed (pancuronium), and artificially ventilated dogs. The carotid artery, the external jugular vein, and the thoracic duct were cannulated. Following a control period, GB was performed by pentolinium tartrate and thereafter the other drugs were infused in a random sequence for 30-60 min with 1 h intervals. Mean arterial blood pressure was decreased from 125 to 90 mmHg by GB, it was increased by 36 mmHg by AD, 41 mmHg by NA, and 44 mmHg by AII, and was decreased by 27 mmHg by IP. LF was about 38 microliter/min/kg before GB and was not changed systematically by GB, because either the sympathetic tone was rather weak or the intrinsic contractions and the tone of lymphatics were reduced by GB. FER was not affected by GB. LF increased by 9 microliter/min/kg (control 36 microliter/min/kg) during AII infusion, probably due to increased lymph formation; the latter can be concluded from the 68% increase in FER. NA raised LF by 15 microliter/min/kg (control 44 microliter/min/kg) probably due to alpha-adrenergic stimulation of the intrinsic contractions of lymphatics; lymph formation seemed not to be affected because FER was not changed systematically. AD enhanced LF by 29 microliters/min/kg (control 39 microliters/min/kg).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1984

Ribose intervention in the cardiac pentose phosphate pathway is not species-specific.

Ribose is cardioprotective in the rat in a variety of pathophysiological conditions. The metabolic basis for this effect is the low capacity of the oxidative pentose phosphate pathway in the myocardium. Ribose bypasses this pathway, elevates the available pool of 5-phosphoribosyl-l-pyrophosphate, and thus stimulates the biosynthesis of adenine nucleotides. In this study reported here the activity of glucose-6-phosphate dehydrogenase, the first and rate-limiting enzyme of the oxidative pentose phosphate shunt, was very low in the human heart and was of the same order of magnitude in the myocardium of various animal species. Furthermore, ribose had a similar stimulating effect on myocardial adenine nucleotide biosynthesis in the guinea pig, in which hemodynamic parameters are different from those in the rat. It is concluded that the metabolic basis for the effectiveness of ribose is similar in all species investigated.

Adenine Nucleotides↗
PubMed1981

[A time-saving empirical method to calculate the area under dye dilution curves for the determination of cardiac output (author's transl)].

A simple and time-saving method is given for calculation of the area under dye dilution curves. The analysis of 415 dye dilution curves had shown that the area (A) under the curve, corrected for recirculation by semilogarithmic extrapolation and integrated by planimetry, could be approximated by the product of the concentration peak height (H) and the distance (t75) between the time of indicator appearance and the time of decay of indicator concentration to 75% of peak concentration: A = H.t75. The mean difference between cardiac outputs calculated from such "empirical" areas and from extrapolation-planimetry areas was 6.1 +/- 4.6% (n = 531). About 95% of the "empirical" values were within +/- 15% of the "planimetric" data. No systematic difference was observed for cardiac outputs from 50 to 350 ml/min/kg. Comparison of the presented method with other empirical methods shows, that the presented approximation of dye dilution curves has some advantages. The presented method (and all other empirical methods), however, should not be employed if high precision is required.

Cardiac Output↗
PubMed1977

Studies on the suitability of a cyanine dye (Viher-Test) for indicator dilution technique and its application to the measurement of pulmonary artery and aortic flow.

The spectrum of a cyanine compound [Viher-Test (VT)] was recorded in distilled water, 5% glucose, 0.9% NaCl. The absorption maximum of these solutions was at 760 nm; after adding to plasma or blood the maximum was shifted to 785 nm. The time required for this spectral stabilization was less than 1 s at 37 degrees C for VT in H2O or glucose, it was slowed to 7 s at room temperature, and for VT in NaCl it was more than 30 s at 37 degrees C. VT binds to plasma proteins to at least 95%. The absorbance of VT in H2O (1000 mg/l) decreased by 1.0% per hour. Toxicity (LD50) of VT in H2O given i.v. in mice was 115 mg/kg body weight. Dye dilution determination of the flow in an artificial circulation with VT was within +/- 5% of direct measurements. Data indicate that VT is as suitable as Cardiogreen for indicator dilution technique using cuvette densitometer or reflection photometry. Simultaneous determinations of pulmonary artery and aortic flow from one dye bolus showed no significant difference on the average, but pulmonary artery flow diverged by up to +/- 25% from aortic flow due to incomplete mixing of dye and blood, respiratory changes of cardiac output or transient differences in right and left heart output.

Animals↗
PubMed1977

Thoracic duct lymph in conscious dogs at rest and during changes of physical activity.

In conscious dogs with a thoracic duct-venous shunt, lymph flow (LF), protein concentration (LP), transported protein (LTP), albumin concentration (LA), globulin concentration (LG), albumin to globulin ratio (LAG), plasma disappearance rate of labelled albumin (k), plasma volume (PV) and intravascular protein pool (IVP) were studied at rest, during walking and muscle relaxation induced by guajacolglycerinether. At rest, LF approximated 50 mul/min-kg and LTP 1.55 mg/min-kg. LF and LTP correlated positively with the state of physical activity. LP was 54%, LA 67%, LG 43%, but LAG 156% of the plasma values; k was 0.00228. Relaxation reduced LF by 34%, LTP by 31%, LAG by 7% and the lymph concentration of i.m. applied labelled albumin by 54%. PV, IVP and k were not changed significantly. Walking enhanced LF by 100%, LTP by 50% and LAG by 25%. LP was decreased by 15%. PV, IVP and k were not changed significantly. Control data suggest a significant influence of anaesthesia on thoracic duct lymph flow, composition and protein transport. Spontaneous and experimental changes of thoracic duct lymph may be explained by changes of the activity of the "tissue pump". An extravascular fluid and protein pool would seem to be accumulated at rest and emptied during exercise.

Albumins↗
PubMed1976

Reduction of renal nerve activity by volume expansion in conscious cats.

In conscious cats with intact or denervated baroreceptors volume expansion of 5-15% of blood volume was performed with dextran and isotonic sodium chloride. Renal sympathetic activity (RSA), electroencephalogram (EEG) blood pressure (BP) and heart rate (HR) were recorded. RSA was reduced by 25-85% in 10 experiments out of 11 by volume expansion both with dextran and isotonic sodium chloride. Reduction of RSA could not be related to different states of wakefulness as indicated by the EEG, so could only be caused by volume expansion, although no quantitative correlation could be detected. No differences were observed between animals with intact and denervated baroreceptor. In most experiments BP and HR decreased during volume expansion up to -25 mmHg and up to -23 beats/min, respectively. The degree of BP and HR reduction could not be related to the degree of RSA reduction. The results suggest that changes in RSA might be involved in the renal response to volume expansion.

Animals↗
PubMed1975

Influence of intracranial osmotic stimuli on renal nerve activity in anaesthetized cats.

In baroreceptor denervated cats one internal carotid artery (ICA) or the cerebral ventricular system (CVS) was perfused with isotonic, hypertonic and hypotonic sodium chloride solutions. Renal sympathetic activity (RSA) and blood pressure (BP) were recorded. ICA perfusion with isotonic sodium chloride (150 mM NaCl) produced no changes of RSA compared to control level,. RSA was increased from plus 30% to plus 350% in 44 tests out of 45 tests following hypertonic (425 mM NaCl) ICA perfusion. RSA was decreased following hypotonic (aqua dest.) ICA perfusion from minus 30% to minus 100% in 37 tests out of 50 tests. The degree of RSA changes was found to depend upon the osmolarity of the solutions. 425mM NaCl and aqua dest. produced greater RSA changes than 290 mM NaCl and 75 mM NaCl. CVS perfusion with isotonic sodium chloride produced a slight increase of RSA compared to control levels (plus 15%). Hypertonic sodium chloride produced a RSA increase from plus 15% to plus 135% in 10 tests out of 14 tests. Hypotonic sodium chloride produced a RSA decrease from minus 15% to minus 80% in 8 tests out of 14 tests. Changes of RSA following ICA perfusions and CVS perfusions were accompanied by changes of BP in the same direction. A quantitative correlation between delta RSA and delta BP could not be found. Results suggest that renal osmoregulatory response to osmotic stimuli in the carotid artery may not just arise in response to changing ADH levels but may also be induced by changes in RSA.

Anesthesia↗