ACE-INHIBITOR PREMEDICATION ATTENUATES SYMPATHETIC RESPONSES DURING SURGERY

We studied cardiovascular and catecholamine responses for 3 days in th ree groups of patients undergoing abdominal hysterectomy. The night be fore surgery and again 2 h before induction of anaesthesia, patients r eceived the ACE inhibitor, ramipril, the beta, blocker, metoprolol, or placebo. in the actively treated groups, mean diastolic pressure was reduced during surgery and increases in heart rate and arterial pressu re after surgical incision were attenuated During operation, stroke vo lume (SV) and cardiac output (CO) were significantly higher in the ram ipril group. in contrast, beta, adrenergic block caused no significant changes in SV or CO. The concentration of noradrenaline in plasma and urine indicated that ACE inhibition caused attenuated release of nora drenaline. The results support the concept chat angiotensin II facilit ates release of noradrenaline from sympathetic nerves and that ACE inh ibition inhibits this release.