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Biomedical subjects

L Takács

Publications and source records attributed to L Takács.

At least 91 records · Page 5Linked to original sources
PubMed1979

Regulation of myocardial oxygen consumption by perfusion pressure in isolated fibrillating canine heart.

In order to evaluate whether perfusion pressure or coronary flow affect myocardial oxygen metabolism, oxygen consumption of the isolated fibrillating blood-perfused canine heart was investigated at perfusion pressures of 100, 150, and 200 mm Hg. To obtain different coronary flow rates at a given coronary perfusion pressure, alpha-adrenergic blockade by phenoxybenzamine (10 mg/kg b.w.) was applied, resulting in an increase in coronary flow and a decrease in myocardial oxygen extration. Myocardial oxygen consumption was increased by elevation of perfusion pressure in both the control and phenoxybenzamine-pretreated group. At the same level of perfusion pressure there was no significant difference between the oxygen consumption of control and phenoxybenzamine-pretreated preparations. It can be concluded that in the isolated fibrillating canine heart oxygen consumption is primarily regulated by perfusion pressure, and is independent from coronary blood flow.

Animals↗
PubMed1979

Effect of haemorrhagic hypotension on the circulation of rats with Guérin carcinoma.

After transplanting Guérin carcinoma in rats the cardiac output (Evans-blue dilution), the distribution of cardiac output (Sapirstein's isotope indicator fractionation technique), the nutritive blood flow of the organs, and their circulatory resistance were investigated in haemorrhagic hypotension (40 or 70 mm Hg). The posthaemorrhagic redistribution of cardiac output in tumor-bearing rats was similar to that found in normal bled animals: the renal and skin fractions of cardiac output decreased and that of the brain, myocardium, and carcass increased. As a result of bleeding the decrease of the tumor fraction of cardiac output was the greatest compared to the other organs. Thus the tumor seems to be the main target organ of the posthaemorrhagic redistribution.

Animals↗
PubMed1978

[Ileofemoral flaps--a clinical study (author's transl)].

The authors reveiw the anatomy, circulation, planning and techniques of preparing ileofemoral flaps. The possibilities of application of these flaps, advantages and disadvantages of the procedure are discussed. The authors use ileofemoral flaps as a new effective procedure for covering sores of the trochante area.

Blood Circulation↗
PubMed1978

[Neural regulation of substance transport in the kidney].

The denervation diuresis and natri uresiswere manifest in anesthetized dog and rats after acute or chronic renal sympathectomy with no changes in RBF, GFR or in their intrarenal distribution. Micropuncture showed the principal site of action of renal denervation on to be within the proximal tubule. The unchanged relationship between reabsorbed sodium and consumed oxygen suggested that active transport of Na decreased on denervation. No causal relationship between denervation natri uresis and decreased release of renin was revealed. As tubular transport of d-glucose, inorganic phosphate, para--aminohippurate and of uric acid was suppressed by the sympathectomy, the renal sympathetic activity seem to be able to regulate the proximal tubular transport functions.

Animals↗
PubMed1978

Effect of external compression on the postocclusion hyperaemic response of the coronary arteries in the isolated fibrillating dog heart.

The effect of external compression on the postocclusion hyperaemic responses (occlusion time 15, 30, 60 sec) has been studied on the fibrillating canine heart. The heart was placed in a closed organ box containing physiological saline solution, and the coronaries were perfused with blood from a donor dog using a constant volume perfusion technique at 150 mmHg perfusion pressure. The pressure in the organ box varied between 0--50 mmHg. As the compression pressure increased in the organ box, coronary blood flow, basal conductance as well as the parameters of the postocclusion hyperaemic reaction (peak conductance, reactivity, mean transit time of hyperaemia, postocclusive conductance area, and repaymen) decreased. The factors (tissue diffusion, tissue pressure, transmural pressure) at the capillary level can influence the regulation of the postocclusion vasodilatation and the results cannot be explained by metabolic and/or myogenic processes alone.

Animals↗
PubMed1977

Effect of splanchnicotomy on the renal excretion of d-glucose in the anaesthetized dog.

The effects of acute intravenous d-glucose (G) loading were studied on anaesthetized, unilaterally splanchnicotomized ("renal denervation") dogs. Glomerular filtration rate (GFR) was generally not different on the innervated and denervated side, while urine flow (V), sodium excretion (UNaV) and urinary excretion (UGV) of glucose on the splanchnicotomized side were significantly increased at any plasma G concentration. Tubular reabsorption (TG) as well as Tm of G in denervated kidneys was considerably depressed. In a series of experiments with moderately elevated plasma glucose level glucosuria on the sympathectomized side was found that seems to be the consequence of a lower threshold for G in denervated kidneys. The positive correlation between the tubular reabsorption of Na and G was not influenced by renal denervation.

Animals↗
PubMed1977

Effect of splanchnicotomy on the renal excretion of uric acid in anaesthetized dogs.

The renal excretion of uric acid was examined during acute i.v. urate (Ua) loading on unilaterally splanchnicotomized ("renal denervation") anaesthetized mongrel dogs. Glomerular filtration rate (GFR) in general was not different in innervated and denervated kidneys, whereas urine flow (V) and urinary excretion of sodium (UNaV) on the splanchnicotomized side were significantly increased at any plasma concentration of Ua. The excretion (UUaV) and tubular transport (TUa) of urate calculated for unit GFR were considerably increased and depressed, respectively, at normal plasma Ua level and during minor urate loading (plasma concentration up to 4.7 mg%). Above this plasma level, i.e. up to 24.6 mg%, no difference in net urate reabsorption between intact and sympathectomized organs was found. It is suggested that both reabsorption and secretion of Ua in denervated kidneys are diminished.

Anesthesia↗
PubMed1977

Effect of splanchnicotomy on the renal excretion of para-aminohippuric acid in the anaesthetized dog.

Renal excretion of para-aminohippuric acid (PAH) was studied during PAH loading on unilaterally splanchnicotomized ("denervated") anaesthetized dogs. Urine flow, sodium excretion of denervated kidneys were significantly increased. Below a plasma concentration of 20 mg% there were no differences between intact and denervated kidneys in urinary excretion and in calculated tubular transport of PAH. However, maximum secretion rate on the splanchnicotomized side was significantly decreased (innervated: 34.8, denervated: 25.2 mg/100 ml GFR, respectively). Although both Na reabsorption and PAH secretion are impaired by denervation, the exact mechanism of action of renal sympathectomy is not elucidated as yet.

Aminohippuric Acids↗
PubMed1977

Effect of norepinephrine on myocardial reactive hyperaemia in the isolated fibrillating dog heart.

The effect of intracoronary norepinephrine (NE) infusion in a dose of 2 microgram/min on postocclusion hyperaemic reactions following occlusions of 15 sec, 30 sec, 60 sec, and 120 sec was studied on isolated fibrillating, blood-perfused canine hearts. Basal perfusion pressure was kept at the level of 150 mm Hg; perfusion was done with constant pressure or constant volume. During administration of NE, basal flow and basal coronary conductance increased with both perfusion techniques. In the postocclusion period during administration of NE, peak conductance, maximum conductance, reactivity, mean transit time of reactive hyperaemia, postocclusive conductance area and repayment decreased. The differences found in postocclusion reactions in the control state originated from the different perfusion techniques disappeared when NE was infused. The phenomena may be explained by the stimulation of alpha and beta receptors as well as of myocardial metabolism by NE. The results support earlier views which ascribe a decisive role to vasoactive metabolites in the postocclusion reaction after prolonged occlusions. The decrease in reactive hyperaemia by NE may contribute to the development of angina pectoris.

Angina Pectoris↗
PubMed1977

Effect of vasopressin on myocardial reactive hyperaemia in the isolated fibrillating dog heart.

The effect of 0.15 IU/min vasopressin (VA) administered intracoronarily on postocclusion reactions following 15 sec, 30 sec, 60 sec, and 120 sec occlusions of the left coronaries of the isolated fibrillating dog heart were studied at constant pressure or constant volume perfusion with arterial blood of another dog. Basal perfusion pressure was kept at the level of 150 mmHg. Preocclusion state and postocclusion reactions were characterized by changes in coronary conductance. Peak conductance, maximum conductance, reactivity, time to peak conductance, mean transit time and repayment were computed for characterizing reactive hyperaemia. In the control state the post-occlusive conductance--time curve was higher, but shorter in duration with constant pressure perfusion than with constant volume perfusion. Upon the administration of VA, basal conductance decreased considerably while with constant pressure perfusion the hyperaemic reactions underwent hardly any change. In contrast, using constant volume perfusion, the duration of reactive hyperaemia was shortened by VA. Consequently, the differences in mean transit time observed in the controls resulted from the unequal perfusion techniques disappeared on the application of VA. On both constant pressure and constant volume perfusion, maximum conductance decreased as a result of the decrease in basal conductance, therefore the reactivity of the coronary vessels increased markedly. It is concluded that myogenic vasorelaxation may contribute to reactive hyperaemic responses not only on brief, but also on prolonged occlusion. The basal vascular tone is of importance in the coronary adaptation to ischaemia.

Animals↗
PubMed1977

[Experience with polychemotherapy based on cell synchronization, via intra-arterial infusions. Preoperative treatment of maxillofacial tumors].

Chemotherapy based upon cellular synchronisation via intra-arterial infusion was used in the treatment of 21 carcinomas of the maxillo-facial region. These tumours had never been treated either by surgery, nor by irradiation. This pre-operative treatment was not aimed at altering ghe indication for the type of operation decided upon at the outset. It was found that a combination of Vincristine, Bleomycine, Methotrexate and Dibromdulcide was more satisfactory than other types of chemotherapy. The most important complication of the method was a thrombosis of the common carotid.

Bleomycin↗