抄録
In the present study, a month recording of renal sympathetic nerve activity (RSNA) was carried out to study the potential role of arterial baroreceptor in long-term regulation of RSNA and sodium excretion during sodium loading in freely moving rats. Wistar rats, which were previously sino-aortic denervated, were instrumented chronically with electrodes for the measurements of RSNA and electrocardiogram. At least 7 days after the implantation of the electrodes, the animals were housed in individual metabolic cages and then RSNA, heart rate and sodium balance were measured over three weeks. Animals were allowed to drink 3 different concentration of sodium chloride solutions; that was 0, 50, 308 mEq/NaCl. The rats were exposed to either 3 days sodium loading (308 mEq/NaCl) or unloading (0 mEq/NaCl) following 3 days control (50 mEq/NaCl) period. RSNA remained unchanged during both 308 mEq/NaCl and 0 mEq/NaCl loading. Heart rate also did not change significantly relative to the control levels throughout the period of both 308 mEq/NaCl and 0 mEq/NaCl loadings. Sodium excretion increased and decreased significantly (p<0.05) over the 3 days loading and unloading of sodium, respectively. These results suggest that baroreflex control of RSNA seems to play a minor role in regulating sodium excretion during prolonged sodium loading/unloading in rats. [J Physiol Sci. 2007;57 Suppl:S218]
