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Biomedical subjects

J Knapowski

Publications and source records attributed to J Knapowski.

At least 55 records · Page 3Linked to original sources
PubMed1975

Seasonal differences in drug- and temperature-dependent changes of the sodium transport across the isolated frog skin.

In two series of experiments, one conducted in the spring (May-June) and the other in the fall (September-November), the influence of raising temperature of the medium and of vasopressin, insulin and ethacrynic acid on polarized sodium transport in the epithelium of frog skin in vitro was studied. Net sodium transport was determined electrometrically, and active and passive components of transport by the isotope method. Raising temperature markedly increased both components, as well as net flux and electric potential of the membrane in the spring months, but not in the fall. Regardless of the character and extent of the effect on transport, raising temperature of the medium had no qualitative or quantitative influence on the action of vasopressin, insulin or ethacrynic acid.

Animals↗
PubMedDate not supplied

Effect of methotrexate, doxorubicin and mitoxantrone on human peritoneal mesothelial cell function in vitro.

Recent studies have demonstrated that intraperitoneal instillation of dialysis solutions and drug additives may adversely affect the function of peritoneal cell populations. Therefore the aim of the present investigation was to examine the short-term effects of antineoplastic agents on human peritoneal mesothelial cells (HPMC). We have assessed the integrity of HPMC membrane and mechanisms of intracellular potassium transport. There was no evidence of significant cytotoxicity (as measured by 86Rb release) during a 60-min exposure of HPMC to either methotrexate (10(-6)-10(-4) M), doxorubicin (10(-7)-10(-5) M) or mitoxantrone (10(-7)-10(-5) M). In HPMC exposed to doxorubicin (10(-6) M) the intracellular transport of potassium, as assessed with 86Rb as its analogue, was not affected. Methotrexate (10(-5) M) diminished Na,K-ATPase activity and simultaneously enhanced the 86Rb transport via furosemide-sensitive pathway. Mitoxantrone reduced the furosemide-sensitive 86Rb influx in a dose-dependent manner and at a concentration of 10(-4) M it also impaired the ouabain-dependent 86Rb influx. These data demonstrate that antineoplastic agents interfere with HPMC function which might contribute to the oncostatic-induced peritoneal toxicity.

Cells, Cultured↗
PubMedDate not supplied

The effect of halothane on active transport of sodium in the epithelial cell.

The authors studied the effect of halothane on active transport of sodium in the epithelial cells using the method described by Ussing with frog skin as an experimental model. It was found that the action of the anasthetic agent on the active transport of sodium was biphasic, and this observation confirmed the results obtained with another experimental model. It was observed, moreover, that the mechanism of halothane action on the cell membrane it not identical with that of vasopressin, which was used in some of the present experiments before adding halothane. The present investigations suggest that halothane acts primarily on the cell membrane and not on the deeper situated intracellular structures.

Animals↗
PubMedDate not supplied

[Gentamicin may have an influence on the effectiveness of peritoneal dialysis].

An effect of gentamicin on urea and uric acid transfer through peritoneum was studied in rabbits in vitro. It was found that gentamicin decreases urea transfer by approximately 30%. Its effect on uric acid transfer was transient so as mean values of this parameter did not differ statistically before and after antibiotic administration. It may be assumed that gentamicin decreases permeability of peritoneum for certain low molecules of endogenic origin. Such an effect may prove unfavourable when peritoneal dialysis efficiency is concerned.

Animals↗
PubMedDate not supplied

[Effect of pyrazinoic acid on the transport function of the peritoneum--experimental studies].

Bidirectional transport of the urea, uric acid and albumin across parietal peritoneum was investigated in vitro under both normal conditions and following an administration of pyrazinoic acid. It was found that pyrazinoic acid decreased urea and uric acid transport from interstitial to mesothelial surface of the peritoneal membrane but did not affect the transport in reverse direction. Bidirectional transport of albumin remained unchanged. The obtained results are similar to those reported earlier and suggest that pyrazinamide actions are partially selective.

Albumins↗
PubMedDate not supplied

Relationship between stimulation of sodium transport across frog skin and Ledakrin concentration.

Relationship between stimulation of sodium transport across frog skin and Ledakrin concentration. Acta Physiol. Pol., 1979, 30 (2): 261--265. Using the method of measurements of the short circuit current, introduced by Ussing, the relationship was investigated between stimulation of sodium ion transport across frog skin and the concentration of Ledakrin. It was found that the optimum concentration of the drug for investigating changes in ion transport is 10(-5) g per 1 ml of medium.

Acridines↗