Sodium exchange and distribution in the arterial wall

¹ Centro de Investigaciones Cardiológicas and Cátedra de Física Biológica, Facultad de Ciencias Médicas, Buenos Aires, Argentina

Pieces of dog carotid artery were studied with respect to water and sodium content. Total sodium content averaged 113 ± 1.2 mm/kg fresh tissue; total water 73.6 ± 0.3% and inulin space 36.2 ± 0.5% of tissue wet wt. A total of 94.8 ± 1.3% of sodium exchanged within 6–12 min with Na²², and 97.4 ± 0.7% of the stable sodium was extracted in sodium-free solution (choline replacement). The curve of efflux of Na²² at 37 C could be decomposed into three simple exponentials with half-times of 42.5 ± 2.3 sec (phase 1), 5.0 ± 0.3 min (phase 2), and 71.0 ± 7.3 min (phase 3). Exchange of sodium of phase 1 (extracellular) fitted well with a theoretical diffusion curve, showed low temperature coefficient and no potassium dependency, and was not influenced by ouabain. Exchange of sodium of phase 2 (cellular) showed high temperature coefficient and potassium dependency and was sensitive to ouabain. Calculations based on the compartmental analysis indicate a too-great intracellular sodium concentration. Binding of sodium to polyanions in the extracellular space is suggested as a possible explanation of the results.

Key Words: sodium fluxes • sodium vascular muscle • bound sodium • ouabain effects

Submitted on March 3, 1965