ABSTRACT
The possibility that hyperbaric helium can modify membrane function in nonneural cells was investigated by measuring the effect of pressure (29.6 atm He + 1.0 atm O2) on transport of the organic anion p-aminohippurate (PAH) and the organic cation tetraethylammonium (TEA) by renal cortex slices. Control slices were exposed to 100% O2 at 1 ATA. A unique incubating and shaking apparatus was built to allow remote control of the incubation conditions in a sealed chamber containing hyperbaric O2. In rat or rabbit renal tissue incubated for 90 min, pressure did not affect the uptake of either substance and was without effect on the total water content and inulin space of rat renal cortex. The kinetic characteristics of the transport systems were investigated by incubating tissue for 15, 30, 45, 60, 75, or 90 min. These experiments were analyzed by fitting a mathematical model to the data and calculating values for parameters representing the active and passive components of the transport processes. Pressure did not affect either of the parameters for PAH or for TEA transport. Thus, if helium elicits its known neural effects through an action on cell membranes, that action is not large enough to be detected by this assay system.
Subject(s)
Aminohippuric Acids/metabolism , Atmospheric Pressure , Helium , Kidney/metabolism , Tetraethylammonium Compounds/metabolism , p-Aminohippuric Acid/metabolism , Animals , Biological Transport, Active , Cell Membrane Permeability , In Vitro Techniques , Kidney Cortex/metabolism , Kinetics , Male , Models, Biological , Rabbits , Rats , Rats, Inbred StrainsABSTRACT
The pH of bathing media containing acetate increased substantially during a 90-min incubation of renal cortex slices from rats and rabbits and did not achieve a steady state after 5 h. Alkalinization of the medium was markedly depressed by cold (0 degree C) and nearly abolished by incubation under 100% N2. Ammonia synthesis did not appear to be an important additional source of base. Incubation of tissue from either species in acetate-free medium reduced but did not abolish base production. Acetazolamide further reduced base production by rat kidney. It was concluded that a portion of the base added to the medium by rat renal tissue reflects the operation of a transport process that separates hydrogen and hydroxyl ions and may be the same one that normally secretes hydrogen ion into tubular fluid.
Subject(s)
Kidney Cortex/metabolism , Acetates/metabolism , Acetazolamide/pharmacology , Acidosis/metabolism , Ammonia/metabolism , Animals , Buffers , Culture Media , Hydrogen-Ion Concentration , In Vitro Techniques , Male , Rabbits , Rats , Rats, Inbred StrainsABSTRACT
The stimulating effects of elevated medium pH and androgen on in vitro transport of p-aminohippurate and N-methylnicotinamide (NMN) were additive, although the androgenic effect was pH-dependent only in the case of NMN. The similarity of response of the 2 systems supports the idea of a common passive efflux pathway for organic anions and cations.
