Influence of increased sodium intake on cerebral excitability.

The purpose of the study has been to observe the influence of an increased dietary sodium intake over cerebral excitability in rats. Research was conducted on two lots of animals: the first lot (PSA) was maintained under the influence of an increased intake of sodium given in the form of physiologic solution, instead of water. That regimen was started during gestation and continued after birth for another 12-14 months before the rats were sacrified. The second lot was given distilled water (DWA) in an identical manner. In other respects, the diet was similar for both lots We compared the following parameters: a) Electrophysiological (electrocorticogram); b) Hydroelectrolytic balance; c) Sodium concentration capacity of the kidney; d) Mineral-corticoid response; e) Motor and motivational behaviour. The data we obtained point to: 1. A shifting of the ECG frequency spectrum towards higher frequency in rats that consumed NaCl in excess. 2. PSA consume significantly more saline solution than DWA, therefore liquid consumption is also greater. Renal elimination of water, Na and K is significantly greater is PSA compared to DWA. Moreover, DWA conserve sodium while PSA conserve water, the respective values being different in a considerable degree in the two lots. 3. The value of the (urinary Na/urinary K) ratio is double in PSA compared to DWA, pointing to a decrease in mineral-corticoid secretion. 5. The animals that have chronically consumed a hypersaline diet show a significantly greater motor agitation compared to the DWA. When free to choose from among physiological solution, water and glucose solution, PSA show no preference for sodium: this points to the absence of obtained motivation for the saline solution The data support the idea that a chronically increased content of dietary NaCl stimulates cerebral excitability.