Effects of enalaprilat on sympathetic activity and metabolism of exercising muscles in rabbit.
1. To investigate the effects of angiotensin-converting enzyme inhibition (ACEI) on exercise performance, the following were measured in eight normal rabbits performing graded treadmill exercise during intravenous vehicle saline or enalaprilat infusion: haemodynamics, noradrenaline (NA) spillover, hindlimb oxygen consumption and lactate release. 2. Blood pressure, heart rate (HR), femoral blood flow (FBF), hindlimb lactate release, hindlimb oxygen consumption and hindlimb NA spillover rate were all significantly increased during exercise and the changes during enalaprilat infusion were similar to control responses. 3. At submaximal exercise (6 m/min), ACEI did not significantly alter the responses of hindlimb lactate release, NA spillover rate or oxygen consumption. At the higher exercise load (12 m/min), ACEI reduced hindlimb NA spillover rate (33.1 +/- 4.2 vs 61.3 +/- 17.1 ng/min) and significantly increased oxygen consumption (241 +/- 53.4 vs 133 +/- 23.3%, P < 0.05). The ratio of hindlimb NA spillover rate to total NA spillover rate was markedly increased during exercise, with similar changes being observed in ACEI and control experiments. 4. This study indicates that acute ACEI has a favourable effect on oxygen utilization in exercising muscle in the normal rabbit. Suppression of local sympathetic activation during exercising stress, as reflected in a reduced NA spillover response, may benefit the microcirculation in exercising muscles.
Monash University Department of Medicine, Monash Medical Centre, Clayton, Victoria, Australia.
K
K
Shimizu
Z Q
ZQ
Wang
D J
DJ
Way
J
J
Palmos
B P
BP
McGrath
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D015773:Enalaprilat / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006614:Hindlimb; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D009132:Muscles / Q000187:drug effects* / Q000294:innervation / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D005082:Physical Exertion; D011817:Rabbits; D012039:Regional Blood Flow / Q000187:drug effects
D007773:Lactates; D019344:Lactic Acid; D015773:Enalaprilat; D009638:Norepinephrine