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M Michalik

Publications and source records attributed to M Michalik.

77 records · Page 5Linked to original sources

Effect of various aminoglycoside antibiotics on glucose formation in isolated rabbit kidney-cortex tubules.

The effect of six aminoglycoside antibiotics on the rate of gluconeogenesis was studied in isolated rabbit kidney-cortex tubules incubated with various substrates. All antibiotics studied did not affect glucose formation from both malate and 2-oxoglutarate. The rank order of the drug-induced inhibition of glucose formation from lactate, pyruvate and propionate was the following: neomycin = gentamicin greater than tobramycin greater than kanamycin = amikacin greater than streptomycin. This in principle corresponds to their ability to diminish pyruvate carboxylation in isolated kidney-cortex mitochondria, as well as to their known nephrotoxic potential observed in vivo. Aminoglycoside antibiotics decreased the respiration of tubule suspension incubated with various substrates. However, the rank order of the inhibition by antibiotics of oxygen uptake was different from that observed for gluconeogenesis, suggesting that the rate of energy generation does not limit glucose formation under conditions studied.

Aminoglycosides↗

Calcium-dependent effect of gentamicin on glucose formation in isolated rabbit kidney-cortex tubules.

In contrast to the inhibition by gentamicin of glucose production from propionate, pyruvate and lactate in renal tubules incubated at 2.5 mM Ca2+, this antibiotic does not affect gluconeogenesis from propionate and lactate, and significantly stimulates this process from other substrates at 0.5 mM Ca2+. This may be due to the gentamicin-induced increase of the cytosolic manganese content (from 1.7 to 2.7 nmol/mg protein), resulting in a stimulation of cytosolic phosphoenolpyruvate carboxykinase activity. At 2.5 mM Ca2+ the cytosolic Mn content (2.7 nmol/mg protein) seems to be high enough to accomplish activation of the enzyme.

Animals↗