PubMed Health⌕ Search

Biomedical subjects

U Heckmann

Publications and source records attributed to U Heckmann.

13 recordsLinked to original sources
PubMed1990

Evidence for a preglomerular oxygen diffusion shunt in rat renal cortex.

Although blood flow to the renal cortex is high and oxygen extraction is low, the renal cortex is remarkably susceptible to hypoxia. Because erythropoietin production has been localized mainly to the renal cortex, the aim of this study was to find a common denominator for both the high susceptibility to hypoxia and oxygen sensing within the renal cortex. By direct measurement of oxygen pressure with microcoaxial needle sensors at superficial glomeruli of the in situ kidney of anesthetized Munich-Wistar-Frömter rats, we obtained mean partial pressure of O2 (PO2) values of 46 +/- 13 (SD) mmHg (n = 71). The simultaneously measured systemic PO2 in arterial blood was 90 +/- 8 mmHg (n = 54). Changing the respirator gas from air to pure oxygen enhanced systemic arterial PO2 to 593 +/- 27 mmHg, whereas PO2 at the superficial glomeruli increased only to a mean of 80 +/- 28 mmHg (n = 71). These data suggest significant preglomerular shunting of oxygen within the cortical vasculature, most likely between interlobular vessels, which are arranged in a countercurrent fashion and represent quantitatively the largest contact area between arteries and veins within the renal cortex.

Air↗
PubMed1989

Renal mesangium is a target for calcitonin gene-related peptide.

Rat calcitonin gene-related peptide (CGRP alpha; EC50, 1 nM) was shown to stimulate cAMP formation in cultured rat renal mesangial cells. CGRP concentration dependently (EC50, 1 nM) also inhibited contraction of mesangial cells by angiotensin II (10 nM). Angiotensin II (10 nM) caused a transient increase of the intracellular calcium concentration from 140 nM to 480 nM in the mesangial cells, but these calcium transients were not altered by CGRP. CGRP (10 nM) decreased vascular resistance in the isolated rat kidney perfused at constant pressure (100 mm Hg; P less than 0.01). The decreased vascular resistance was accompanied by a rise of the glomerular filtration fraction. CGRP, moreover, attenuated the effects of angiotensin II on renal vascular resistance and glomerular filtration (P less than 0.01). In conclusion, CGRP causes relaxation of renal mesangial cells and decreases renal vascular resistance. As a result CGRP raises glomerular filtration and the filtration fraction. The effect may be linked to cyclic AMP formation. Thus, regulation of renal vascular and glomerular function may represent a novel action of CGRP apart from its cardiovascular effects.

Angiotensin II↗
PubMed1989

Sodium reabsorption in the isolated perfused kidney of normotensive and spontaneously hypertensive rats.

Kidneys of 3-month-old spontaneously hypertensive rats (SHR) of the Münster strain and age- and weight-matched normotensive rats (Wistar-Kyoto; WKY) were isolated and perfused at a constant pressure of 100 mmHg with a modified, albumin-free Krebs-Henseleit solution. Fractional Na+ reabsorption, which is independent of the glomerular filtration rate under these conditions, was significantly elevated in SHR kidneys compared with WKY kidneys during 90 min of perfusion (P less than 0.01). Renal perfusion flow rates did not differ between SHR and WKY. These data support the concept of an intrinsic renal abnormality in Na+ excretion that may contribute to the maintenance of hypertension in SHR.

Absorption↗
PubMed1989

Transmission of hypertension in rats by cross circulation.

Cross circulation was performed in 54 couples of spontaneously hypertensive and normotensive rats. Blood was pumped through two anastomoses between the carotid arteries and external jugular veins in both directions with equal flow rate. In normotensive rats cross-circulated with untreated spontaneously hypertensive rats mean arterial pressure increased by 20.9 +/- 12.2 mm Hg (p less than 0.01). Administration of digoxin antibody in a dose binding 0.25 mg digoxin to the spontaneously hypertensive rats before cross circulation prevented the transmission of hypertension to the normotensive rat, whereas chemical sympathectomy with 6-hydroxydopamine and intravenous injection of inactive Fab fragments had no inhibitory effect. It is concluded that, in this strain of spontaneously hypertensive rats, a circulating hypertensive factor exists. The factor binds to digoxin antibody and is not produced in sympathetic nervous tissue.

Animals↗
PubMed1987

Arterial resistance vessels in primary hypertension--evidence for altered cellular Ca2+ metabolism.

The role of intracellular free Ca2+ in arterial smooth muscle was investigated in aortic smooth muscle cells from spontaneously hypertensive and normotensive rats, as well as in porcine aortic smooth muscle. Intracellular free Ca2+ in aortic smooth muscle from spontaneously hypertensive rats was elevated. Incubation of porcine aortic smooth muscle with plasma from essential hypertensive and normotensive subjects revealed a humoral factor in subjects with essential hypertension, which increased intracellular free Ca2+. Cross-circulation experiments between spontaneously hypertensive and normotensive rats demonstrated a transmission of hypertension to the normotensive animals as a result of a circulating hypertensive factor possibly produced in the kidneys and adrenals. The experiments suggest that vasoconstriction in primary hypertension may be caused by a humoral factor that increases intracellular free Ca2+ in arterial smooth muscle.

Animals↗
PubMed1975

[Complex therapy].

Complex therapy. On the occasion of the Symposium of the Society of Orthopaedic Stomatology of the German Democratic Republic at Reinhardsbrunn (Thuringia) from April 8 to 11, 1974, questions of complex therapy were dealt with in the framework of the main subject "The Effectiveness of Orthodontic Treatment in Adolescents". The present contribution was the discussion basis on the second day of the meeting.

Adolescent↗
PubMed1975

[Studies of longitudinal section on jaw development and resulting conclusions for orthodontic treatment planning in the deciduous dentition].

From a 11 years' longitudinal study of the tooth development in 93 children conclusions are drawn as to the planning of orthodontic treatment in the deciduous dentition. In accepting the task of orthodontic treatment, the dentist assumes a very responsible function which he will only master if he knows the various patterns of dental development. The difficulties of a prognosis as to dental development in an individual child are exemplified by the evaluation of dental findings obtained at the different years of life.

Cephalometry↗
PubMed1975

[The narrowing of the support area by premature tooth loss and caries in various abnormal alignments].

On the basis of the findings from 1470 patients referred for orthodontic treatment, the authors analyse, for various types of anomalies, the sequelae of untreated proximal caries and premature extractions in the supporting areas of the upper and the lower jaw. The results obtained indicate that the premature loss of deciduous teeth causes, in case of malalignment associated with lack of space, secondary alterations.

Dental Caries↗