Aging differentially modifies sensitivity of nerve blood flow to vasocontractile agents (endothelin-1, noradrenaline and angiotensin II) in sciatic nerve

This study examined the influence of the vase-constricting agents (noradren aline, endothelin-1 and angiotensin II) in Sprague-Dawley rats aged 2, 6 an d 24 months by evaluating epineurial arteriolar vasoreactivity in response to superfused teat agents. Nerve blood flow (NBF) was measured using microe lectrode H2 polarography. In 24-month-old rats, NBF was decreased and vascu lar resistance (VR) was increased-compared with 2- and 6-month-old rats. Al l of the constricting agents reduced NBF in the 2-, 6- and 24-month groups, however, the effects of the constricting agents reduced significantly with age. These results suggest that during aging, there is a decline of vasoco nstrictive responses to noradrenaline, endothelin-1 and angiotensin II in p eripheral nerve and that these chances may be due to altered function of re ceptors. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.