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J Knapowski

Publications and source records attributed to J Knapowski.

At least 37 records · Page 2Linked to original sources
PubMed1989

[Human peritoneum in vitro: changes in urate transport after administration of pyrazinoic acid].

The article is an analysis of the dynamics of two-direction transportation of uric acid (UA) through the human peritoneum in vitro, and also changes of the dynamics under the influence of pyrazinoic++ acid. The peritoneum was taken from the anterior abdominal wall of patients undergoing planned abdominal surgery. It was found that the transportation of UA both from the vascular to the mesothelial side of the peritoneal membrane and in the opposite direction remained on a stable level for 120 minutes. The introduction of pyrazinoic++ acid decreased the transportation of UA from the vascular to the mesothelial side of the peritoneum on the average by 50 per cent. The transportation in the opposite direction did not change. The results obtained are consistent with results of clinical examinations. One may suppose that pyrazinoic++ acid induces changes in transportation qualities of the peritoneum.

Adult↗
PubMed1988

An analysis of the edge damage of membranes studied in vitro.

A mathematical formula was developed for estimating the effect of membrane edge damage on the membrane permeability measured in vitro. It was assumed that in the chambers compressed against each other with identical force, the membrane edge damage depends on their radius and is characteristic for different tissues. Transport of rubidium and albumin across the human amnion and the rabbit mesentery was measured in two chambers with different active areas and this made it possible to estimate the extent of membrane edge damage.

Amnion↗
PubMed1987

Transperitoneal transport of methotrexate in vitro.

The study presents estimation of bidirectional transport of methotrexate (MTX) across rabbit's parietal peritoneum in vitro. The experiments were done under iso- and hyperosmotic conditions. In the former case the amount of MTX transported transperitoneally from vascular to mesothelial side of the membrane was higher than that transferred to opposite direction, the values of the transport to both directions were observed to decrease with time. Change of the medium from isoosmolarity to hyperosmolarity resulted in diminished transport from the vascular to mesothelial side of the membrane, as compared to the control. With a stabilization of the transport to opposite direction, the resultant net transport approached zero. Analysis of the obtained results revealed more complicated nature of the mechanism of MTX transport across peritoneal membrane than that of a simple diffusion.

Animals↗
PubMed1984

Augmentation of peritoneal dialysis clearance with procaine.

Local anesthetic procaine in a 0.25% concentration was used as the adjunct to the dialysis fluid during peritoneal dialysis in rabbits. Procaine increased peritoneal clearance of urea (2.213 +/- 0.187 ml/min to 3.544 +/- 0.41 ml/min) and inulin (0.528 +/- 0.079 ml/min to 0.852 +/- 0.213 ml/min). Effect of the drug persisted, despite its lack, during the following cycles. Procaine influenced transmesothelial transfer of urea and inulin in vitro. The effect of the drug was biphasic. During the first 20 min a decrease of both solutes fluxes was observed. Then the transport rate of urea and inulin started to grow. The effect of procaine was independent of the membrane's side to which the drug was added. At least two sites of procaine action (vascular system and mesothelium) during peritoneal dialysis are proposed.

Animals↗
PubMed1984

[Effect of padan on active sodium transport in the epithelium of isolated frog skin].

The effects of " Padan " (hydrochloride of 1.3-di/ carbomylothio /-2-N-dimethylamino/propane/ upon transport capabilities of plasmatic membrane have been checked. The experiment was performed on isolated skin of Rana temporaria frogs. Assessment of transporting activity of membrane in relation to sodium ion involved a method developed by Ussing with so called "short-circuit" technique. The effects of the pesticide on the external and internal surface of the frog's skin have been examined, final concentrations of the compound being 3.4 X 10(-6) M to 3.4 X 10(-3) M. The results indicate that " Padan ", whether administered to the external or internal surface of the membrane, decreases the value of membrane potential and short-circuit current, which is indicative of membrane transport inhibition. The effect varies with pesticide concentration in the medium, though it is statistically significant only in concentration 3.4 X 10(-3) M. On the other hand, membrane resistance usually gets increased as the compound concentration in the medium increases. The results indicate that cellular membrane should be considered while explaining the mechanism of toxic effects of " Padan " upon organism.

Action Potentials↗
PubMed1979

Evaluation of the participation of parietal peritoneum in dialysis: physiological, morphological and pharmacological data.

Bidirectional fluxes of Na+, K+ and Ca++ were estimated under in vitro conditions through isolated patches of rat peritoneal membranes (parietal and visceral). Morphological (TEM) and functional (changes in fluxes) data are presented to show that mesothelium lining the parietal peritoneum forms a barrier than limits diffusion of ions across this membrane. In addition, it was found that Furosemide and nitroprusside change the permeability of the mesothelium for sodium or potassium, respectively.

Animals↗
PubMed1975

The comparative evaluation of methoxyflurane and diethyl ether action upon an active sodium transport across isolated frog skin preparation.

The experiments were performed in vitro using the frog skin preparations and Ussing method. The effect of methoxyflurane was investigated in 18 sections and that of diethyl ether in 16 sections. Both the anaesthetics were found to affect the frog skin preparation in qualitatively similar way. They both demonstrated a two-phase character of action. Decrease in active sodium transport is preceeded by a transient increase in bioelectric indices of the membrane. The effect was reversible after removing of the drugs from the medium. In order to determine the mechanism of action of the two anaesthetics they were given in combination with ADH and insulin. It was found that the mechanism of action of both the drugs is not analogical to any of the hormones examined, at least, as far as the first phase of action is concerned.

Animals↗