抄録
Sympathetic nerve activity has been thought to play a significant role in long-term regulation of physiological functions, including haemodynamics and body fluid metabolism. However, very few attempts have been made to perform long-term recording of sympathetic nerve activity in conscious animals. We have recently succeeded in recording renal sympathetic nerve activity (RSNA) over a month in rats. In this symposium, we would like to describe a technique of long-term recording of RSNA in freely moving rats, and then introduce our recent experiments in which RSNA and sodium balance were measured during 3 days changes in salt intake in rats. Rats were anesthetized with pentobarbital sodium and then renal nerve was exposed; the exposed nerve and the electrode were embedded in a two-component silicone gel. At least 7 days after the implantation of the electrodes, RSNA and sodium balance were measured continuously over three weeks. Animals were allowed to drink four different concentration of NaCl solutions, that was 0, 50, 154, 308 mEq/L NaCl. Sodium excretion changed significantly in proportion to the sodium loading levels of 0, 154 and 308 mEq/L NaCl. However, we found that changes in RSNA were not always correlated with the changes in sodium excretion during changes in dietary sodium intake. It is therefore that long-term recording of sympathetic nerve activity would provide new aspects on roles of sympathetic nerve activity in prolonged adaptive responses of renal and other physiological functions. [J Physiol Sci. 2008;58 Suppl:S20]
