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Biomedical subjects

L Hársing

Publications and source records attributed to L Hársing.

At least 19 recordsLinked to original sources
PubMed1994

Renal hypertrophy in streptozotocin-diabetic rats.

In male adolescent rats kidney mass attained maximum terminal value already at week 1 after streptozotocin treatment, and this value did not change over the next two weeks. At week 1 the kidney size of diabetic rats was greater than that of untreated controls, whereas at week 3 renal mass was the same in both groups. In adult rats with final body and kidney mass streptozotocin treatment failed to induce further increment in renal growth, and the kidney size of diabetic animals was the same as the final kidney size of age-matched control animals. The identity of terminal maximum values for kidney mass in male rats suggests rather an accelerated kidney growth than a true hypertrophic response in diabetes. Similar conclusion can be drawn from our observations made on the compensatory growth of the solitary kidney in diabetic rats with prior uninephrectomy.

Animals↗
PubMed1985

Diuretic and natriuretic actions of extract prepared from rat erythrocytes.

Freeze-dried preparation of rat erythrocytes was extracted into distilled water and after heat treatment the extract was chromatographed on Sephadex G-25 column. The effluent fractions were pooled, freeze-dried, dissolved in Ringer's solution and bioassayed for diuretic and natriuretic responses in anaesthetized non-diuretic rats. The active fractions potently enhanced urine output (about 9-fold control) and urinary sodium excretion (about 7-fold control). The responses started to develop after a lag period of approximately 10-20 min, peaked between 60-80 min post-injection and then diminished. The augmentation of sodium excretion persisted longer than the increased diuresis. The biological activity of the extract was retained after dialysis in a tube with nominal molecular weight cut-off below 1,000.

Animals↗
PubMed1982

Simultaneous activation of coagulation and fibrinolysis after severe renal ischemia in rats.

Coagulation and fibrinolysis were studied during and after bilateral renal artery occlusion for 2 h in rats. After the release of the arterial clamps platelet count and plasma fibrinogen concentration decreased and circulating fibrin monomers were detected. The shortening of euglobulin lysis time and the accumulation of fibrinogen/fibrin degradation products indicated a simultaneous activation of fibrinolysis. Rapid and severe hemolysis was evident by the steadily increasing plasma hemoglobin concentration. Bilateral nephrectomy reversed all these pathological changes.

Animals↗
PubMed1982

Renal structural and functional changes and sodium balance in hypothyroid rats.

Significant retardation in body and kidney growth and in renal glomerular and proximal tubular development was observed in hypothyroid rats in comparison with euthyroid controls. Body mass was found to increase by 40% but kidney mass only by 3.5% over a period of 3 weeks following thyroidectomy in contrast to an average increment of 178 and 113%, respectively, in normal animals. Dissociation was found also in the development of glomeruli and proximal tubules: glomerular size correlated with body weight while tubular size with kidney weight. Single nephron glomerular filtration rate was adapted not to the glomerular as normally but rather to the tubular volume thereby compensating functionally for the dimensional glomerulotubular imbalance. However, despite the decreased filtered and excreted amount of sodium relative to the body weight sodium balance was maintained by depressed tubular reabsorption which was uniformly observed in thyroid deficiency. Because of the uncertainty regarding the direct action of thyroid hormones on the tubular function it is assumed that decreased tubular sodium reabsorption is principally caused by the mechanism subserving the maintenance of sodium balance also in salt loaded normal and sodium sensitive Dahl's rats. This seems to be supported by the exaggerated natriuresis observed both in hypothyroid and sodium sensitive Dahl's rats after saline infusion. Justification of the proposed mechanism needs further investigation.

Animals↗
PubMed1981

Decreased complement activity after bilateral renal ischemia in rats.

The bilateral occlusion of the renal arteries for 2h resulted in a marked decrease of serum complement activity after recirculation. The release of a proteinic factor with anticomplementary activity detectable in vitro in normal kidney supernate is considered a probable cause of the phenomenon. This factor is able to activate the alternative complement pathway in human serum.

Animals↗
PubMed1979

Evaluation of 133Xe clearance curves in the study of lingual blood flow in dogs.

Lingual blood flow was studied in dogs by the 133Xe clearance technique under control conditions, during epinephrine infusion in response to the combined treatment with Regitin and epinephrine. The composite washout curves recorded during control conditions could be resolved into three monoesponential components. It is suggested that the steep initial slope (component I)is caused by the fraction of blood that perfuses the A-V anastomoses of the tongue. Component II and III appear to the effect of epinephrine infusion might indicate the closure of arterio-venous anastomoses containing alpha receptors. Regitin pretreatment could prevent the closure of the arterio-venous anastomoses elicited by epinephrine infusion. The beta receptor stimulating activity of epinephrine migh account for the augmentation of blood flow to lingual musculature.

Animals↗
PubMed1979

Intrarenal distribution of renal blood flow in the rat.

Intrarenal blood flow distribution was studied with the simultaneous use of the 99Tc labelled frog erythrocyte (microsphere) and the radioactive 86Rb fractionation method in the rat. The amount of blood entering the outer cortex (99Tc labelled erythrocytes method) proved to be higher than one perfusing the outer cortex (86Rb method), whereas the amount of blood entering the inner cortex (99Tc method) was less than the amount perfusing the inner cortex and medulla (86Rb method). Hence a group of the preglomerular arterioles in the outer cortex contributes to the blood supply of the inner cortex, on the other hand a group of preglomerular arteries in the inner cortex participates in the postglomerular blood supply of the medulla. Changes in the renal circulation are, however, associated with altered distribution of postglomerular vascular segments supplied by some groups of preglomerular arterioles. From this it is concluded that the postglomerular vessels of the deeper cortical layers constitute a system which is not parallelly coupled but comprises both series- and parallel-coupled sections. The contribution of these sections appears to vary depending on the actual haemodynamic conditions.

Animals↗
PubMed1979

Effect of renal vasodilatation on intrarenal blood flow distribution.

Total renal blood flow (TRBF) and its intrarenal and intracortical distribution were measured before and during renal vasodilatation induced by acetylcholine infusion using the 133Xe washout, 86Rb uptake and radioactive microspheres distribution techniques. A good agreement was observed between TRBF calculated from 133Xe washout and measured with the electromagnetic flowmeter (FM). 86Rb-TRBF was lower than FM-TRBF and, due to the progressive reduction of renal 86Rb uptake, the difference increased with the increase of flow. With the alteration of TRBF the intrarenal distribution of 86Rb uptake did, however, not change significantly and, accordingly there was no redistribution of RBF either between the cortex and medulla, or among the individual cortical zones. The intracortical distribution of labelled microspheres showed, however, moderate flow dependent changes: with the rise of TRBF, due probably to the reduction of the steric hindrance, the estimated fractional perfusion of the inner cortical zones increased. The sum of the per cent 86Rb content of the innermost cortical zone (C4) and of the medulla exceeded the per cent microsphere content of zone C4. It is concluded that the medulla is perfused not exclusively with blood flowing from the juxtamedullar glomeruli. The regional flow values obtained from the 133Xe curves are not comparable with the results obtained by other methods and cannot be attributed to well defined areas of the kidney.

Acetylcholine↗
PubMed1979

Hypertrophic response of the kidney in indomethacin treated rats.

Indomethacin, a potent inhibitor of prostaglandin (PG) synthesis administered to rats in a total dose of 2 x 4.5 mg/kg i.v. for 2 days enhanced compensatory renal hypertrophy following unilateral nephrectomy (UN). The same drug given to rats with intact kidneys in a total dose of 4 x 4.5 mg/kg i.p. in 2 days increased kidney weight renal RNA content and decreased renal acidic ribonuclease activity. It remains to be elucidated whether the suppression of PG synthesis and/or other pharmacological effects of indomethacin account for these findings.

Animals↗