Biomedical subjects

M Wolgast

Publications and source records attributed to M Wolgast.

At least 91 records · Page 5Linked to original sources

PubMed1975

Kinetics of the glomerular ultrafiltration in the rat kidney. An experimental study.

The quantitative relation between the driving forces over the glomerular membrane and the glomerular plasma flow, on the one hand, and the single glomerular filtration rate (SNGFR), on the other, is still uncertain. Micropuncture measurements on Sprague-Dawley rats made it possible to calculate the net driving force over the glomerular membrane. The single glomerular plasma flow was determined from SNGFR and the single nephron filtration fraction (SNFF). The effective plasma flow was measured with PAH for total kidney and for superficial nephrons. The mean glomerular capillary pressure was found to be 62.6 mm Hg. The results indicate a net driving force of about 13 mm Hg at the distal end of the glomerular capillary. SNGFR was found to be 14.1 nl/min-100 g. SNFF amounted to about 0.27. The filtration fractions determined with the PAH method were in the same range. The results indicate a filtration disequilibrium, in contrast to those of Brenner et al. from measurements on a mutant Wistar rat strain. The filtration fractions seemed to be the same in all glomerular populations. It is clear that the SNGFR is pressure dependent. Our earlier findings of a nonautoregulation of the blood flow through the outer glomeruli were also confirmed.

Animals↗

PubMed1975

Effect of elevated interstitial pressure on the renal cortical hemodynamics.

The influence of renal interstitial pressure on the resistance pattern within the superficial cortical vasculature has been investigated from determinations of 1) the glomerular blood flow eith a modified microsphere technique and 2) the intravascular hydrostatic pressures. Interstitial pressure was monitored via a 50 mum PVC-catheter placed into the subcapsular interstitial space. Two conditions were analyzed viz. a) elevation of uretheral pressure to 20 mm Hg and b) venous stasis to 10-15 mm Hg. Both conditions produced an increase in the interstitial pressure from 1-2 mm Hg to about 5 mm Hg as well as an increased hilar lymph flow and protein flow of about the same size. The vascular reactions were different, however. Uretheral stasis (but not the stasis of a single nephron) produced a decreased resistance in the afferent arteriolae with a concomitant increae in the pressures in the glomerular capillaries, and the peritobular capillary network. In contrast, venous stasis produced only small changes in the parameters studied but for the obvious rise in the peritubular capillary pressure. The results suggest that factors other than the interstitial pressure are governing the afferent vascular tone; the tubular wall tension might be one of these factors.

Animals↗

PubMed1975

Acid-base status in dogs during long term anaesthesia.

The acid-base status in dogs anaesthetized with chloralose or combinations of chloralose and barbiturates was studied. No surgical procedures were used to elucidate whether the anesthesia per se changes in the acid-base status. Irrespective of the anaesthetic used, a progressive metabolic acidosis developed after 2-3 hours. This progressed for several hours despite normal arterial blood pressure and pulse rate. A theoretical model, based on the results, is presented. Even the induction of anesthesia caused an impairment of the peripheral circulation. This impairment, in combination with rising body temperature, might be strong enough to cause a detectable metabolic acidosis. It is concluded that, as compared with blood pressure and pulse rate, the acid-base status of the blood is a reliable and early sign of the impairment of circulation during anesthesia.

Acid-Base Equilibrium↗

PubMed1975

Renal transplantation in the rat. IV. Cortical pressure gradients measured in vivo and during isolated perfusion with reference to renal function after transplantation.

Pressure characteristics within the renal cortex of rats were studied with a micropuncture technique in vivo and during isolated hypothermic perfusion. Use of a colloid-free perfusate resulted in an interstitial pressure of 30 cm H2O (normally 1-2 cm H2O), thereby producing a high outflow resistance and perfusion pressure. Interstitial pressures only slightly above normal were found when colloids such as Dextran 40 or albumin were added. The main resistance within the renal vascular bed both in vivo and during isolated perfusion was localized to the afferent and efferent arterioles. The increased pressures were most likely due to extravasation of fluid. With regard to the colloid-containing perfusates, the small but significant increase in interstitial pressure could be explained by increased passage of colloids over the capillary membranes. In conclusion, colloid-free perfusion produced a pronounced but transient elevation of the postoperative serum creatinine level in renal transplant recipients.

Albumins↗

PubMed1974