Biomedical subjects
Publications and source records attributed to F Celentano.
Formulations are given both for narrow (less than 2 pH units) and for wide range (up to 8 pH units) immobilized pH gradients, spanning between pH 2.5 and pH 11. The contribution from water to the buffering power (beta) at these pH extremes requires the recipes to be optimized (in terms of gradient linearity) for each desired level of beta av.
The effect of the interaction between polyacrylamide matrices containing covalently bound acidic and basic residues and free ions was indirectly evaluated from the width of the residual salt fronts after electrophoresis under standard conditions. Around neutrality the front width is larger than at alkaline, and much larger than at acidic pH, and in all instances much higher for anions than for cations. The width decreases faster with the buffering power of the matrix than with its ionic strength. After about 5000 V x h, the migration of the salt front is very slow, and becomes negligible when diffusion is prevented. When inadequately buffered by the matrix, H+ and OH(-)--comigrating with anions and cations--increase the conductivity within the salt front and drastically lower the electrical field strength.
A method allowing the measurement of the electrical quantities related to the physiological functions of the frog skin in situ is presented. The method allows the performance of several experiments on the same pithed animal, which remains alive for a number of days. The preparation is very stable, and the electrical potential difference and short-circuit current values are higher than in isolated skin. The theory of measurement and the possible systematic errors are discussed. The possibilities of the method are evaluated on comparing the pH and temperature dependence of the electrical quantities in situ with previous measurements on isolated skin.
Lead ions and the surfactant nonylphenolethoxylate are found to inhibit the active transport-coupled water flow in the leg skin of Rana esculenta. The water permeability for osmotically driven flows remains unchanged for high flows, while it is remarkable lowered near zero osmotic pressure difference. The possible mechanism of the permeability change is discussed in connection with the available data on the electrophysiological effects of the pollutants.
The volume flow dependence upon the osmotic pressure difference of both impermeant (sucrose) and permeable (NaCl) species has been investigated in leg skin bags of Rana esculenta. It is concluded: 1. The hydration-dehydration error in the flow measurement with leg skin bags is negligible. 2. The flow-force relationship is non-linear. 3. Unstirred layers and solute permeation have little, if any, influence on non linearity. 4. Structural modifications of the skin induced with hypertonic solutions have been observed and may contribute to non linearity, as well as the multiple-barrier effect.
By means of the Kedem-Katchalsky thermodynamic description of active transport, a relationship has been derived between the apparent reflection coefficient and the Staverman reflection coefficient for passive transport of a solute which is both actively and passively transported. The relationship between volumetric flow and its driving forces, containing the Staverman reflection coefficient, was tested for sodium chloride in rabbit gall bladder and the reflection coefficient was evaluated.
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