Immediately after unilateral nephrectomy, the glomerular filtration rate (GFR) and urinary excretion rate increase in the remaining transplanted rat kidney. In a previous study, we found that GFR in a transplanted kidney was reduced through an activation of the tubuloglomerular feedback control. Excision of the rat’s own remnant kidney then reduced feedback sensitivity and thereby allowed GFR to rise. The present study aimed at investigating whether prostaglandins are involved in this functional adaptation. Clearance and micropuncture experiments were performed before and after administration of indomethacin and after subsequent unilateral nephrectomy. GFR and the urinary excretion rate of electrolytes and water were measured. From proximal tubular stop-flow pressure (PSF) measurements the feedback characteristics were determined as the maximal stop-flow pressure response (ΔPSF) to an increase in distal flow and the turning point (TP), i.e. the end proximal flow rate that caused 50% reduction of ΔPSF. The results showed that following nephrectomy the tubuloglomerular feedback sensitivity was decreased, with an increased TP and reduced ΔPSF. Pretreatment with indomethacin (2 mg/kg BW) prevented not only the change in feedback sensitivity at nephrectomy but also the rise in GFR. These results suggest that the prostaglandins play a possible role as one link in the chain of adaptive events occurring immediately after nephron loss.
The microneurovascular replantation of a completely amputated penis is described. Fifteen hours after the replantation an arterial reanastomosis was performed due to a secondary thrombosis. The result after 3 months is excellent, with returned capacity of erection.
The structure of calcium carbide is investigated using thin sections and ground sections. Depending on chemical and other factors, calcium carbide occurs in three types of structure, which are interpreted as conversion products resulting from a high-temperature structure.The pavement-like structure containing CaCJ is present in industrial carbide with a low content of nitrogen. With increasing fraction of lignite high-temperature coke used for carbon supply as a substitute for coal coke in the production of carbide, the particle size decreases, and the micro hardness increases.The interlocked structure with CaC,-I1 and higher contents of nitrogen, which has been detected in carbide produced in the laboratory, is extremely dense. No grain sizes can be given. This kind of carbide produced in the laboratory has a lower micro hardness than industrial carbide.The mixed crystal structure is typical of carbide with a high content of sulphur. CaC,-CaS-I is present as a phase.In all three types, the respective carbide phases have a marked lamellar structure. No typical shapes of crystals can be detected. In consequence of poor crystal formation, the information obtained with a microscope about the phases contained in the material investigated is complemented by X-ray diffraction methods. Mittels entsprechender Diinn-und Anschliffe wird das Gefiige von Calciumcarbid untersucht. Calciumcarbid tritt in Abhangigkeit von chemischen und anderen EinnuDfaktoren in 3 Gefiigetypen auf, die als Umwandlungsprodukte, aus einem Hochtemperaturgefiige entstanden, interpretiert werden. Pnastergefiige mit CaC,-I liegt in technischem Carbid mit niedrigem Stickstoffgehalt vor. Bei wachsendem Anteil des als Kohlenstofftrager anstelle von Steinkohlenkoks zur Carbiderzeugung cingesetzten Braunkohlenhochtemperaturkokses nimmt die Korngrok ab und die Mikroharte zu. Verzahnungsgefiige mit CaC,-I1 und hoheren Stickstoffgehalten, im Laborcarbid nachgewiesen, ist auDerordentlich dicht. Korngrokn lassen sich nicht angeben. Derartiges Laborcarbid hat eine geringere Mikroharte als technisches Carbid. Mischkristallgefiige ist typisch fur Carbid mit hohem Schwefelgehalt. Als Phase tritt CaC,-CaS-I auf. Alle 3 Gefiigetypen zeigen die jeweilige Carbidphase in ausgepragtem Lamellenbau. Typische Kristallformen sind nicht nachweisbar. Mikroskopisch gewonnene Aussagen zum Phasenbestand werden wcgen der schlechten Kristallausbildung durch Rontgenbeugungsmethoden erglnzt.
The prostaglandins (PG) of the renal medulla might affect the nephron and the cortical arteriolar function via the tubular route. To investigate this question PGE2 (1 microgram/mL), PGF2 alpha (10 micrograms/mL), or PGI2 (1 ng/mL) was added to the tubular perfusion solution when the characteristics of the tubuloglomerular feedback (TGF) control were measured. The experiments were performed on Sprague-Dawley rats. The proximal tubular stop-flow pressure (PSF) was measured upstream to a wax block, while at the same time the distal nephron was perfused with prostaglandin-containing or prostaglandin-free solutions at different flow rates varying from 0 to 50 nL/min. The maximal drop in PSF (delta PSF) and the tubular flow rate at which 50% of the delta PSF response was obtained, the turning point (TP), were determined. When PGE2 or PGF2 alpha was added to the tubular perfusion solution in the control animals a significant increase in feedback sensitivity was found. After 10 min of tubular PGI2 perfusion the feedback sensitivity was almost completely abolished, with a delta PSF of 0.8 mmHg (1 mmHg = 133.322 Pa) (control 8.4 mmHg) and a TP of greater than 40 nL/min (control 22 nL/min). After nephrectomy the feedback sensitivity was reduced, with a delta PSF of 2.0 mmHg and a TP of greater than 40 nL/min. When PGE2 was added to the tubular perfusion solution in the uninephrectomized animals, the feedback sensitivity was increased to the control level, with a delta PSF of 8.2 mmHg and a TP of 20.0 nL/min.(ABSTRACT TRUNCATED AT 250 WORDS)
Effects of intraarterial prostacyclin (PGI2) infusions on interstitial hydrostatic and oncotic pressures and on the tubuloglomerular feedback (TGF) control of glomerular filtration rate (GFR) were studied in rat kidneys. The hilar lymph flow rate was used as a measure of interstitial hydrostatic pressure and the lymph protein concentration was used for interstitial oncotic pressure estimation. In the micropuncture experiments the stop-flow pressure technique was employed for determining the TGF characteristics, i.e. stop-flow pressure (PSF), maximal reduction of PSF (delta PSF) and turning point (TP), defined as the end-proximal flow rate at which 50% of delta PSF was obtained. Non-hypotensive doses of PGI2 (50 to 100 ng X kg-1 B.W. X min-1) infused in 30 min evoked an increase in urine and lymph flow rates and a decrease in lymph protein concentration, but did not affect GFR. delta PSF was reduced (9.9 +/- 1.0 mmHg versus 4.7 +/- 2.2 mmHg) and TP increased (22 +/- 2 nl/min versus 34 +/- 2 nl/min), but the PSF was unaffected. These changes were seen during the infusion period and during the immediate post-infusion control period of 30 min. Our data indicate that non-hypotensive doses of PGI2 in some way can affect the renal interstitial pressure and the TGF control system.
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