Effects of single doses of quinapril and atenolol on autonomic nervous function and exercise capacity in healthy volunteers

Abstract

The effects of single oral doses of the angiotensin converting enzyme (ACE) inhibitor quinapril (CI-906) 40 mg and the cardioselective beta-adrenoceptor blocker atenolol 100 mg on sympathetic and parasympathetic function and on exercise capacity have been studied in 8 healthy young men. The trial followed a double-blind, placebo controlled, randomized cross-over design, with at least one week between treatments. Blood pressure (BP) and heart rate (HR) at rest were slightly reduced by atenolol but were not affected by quinapril. Atenolol impaired the sympathetically mediated increases in HR and BP caused by standing, immersion of the hand into melting ice, the Valsalva manoeuvre and isometric forearm exercise. Quinapril did not influence those responses nor the vagally mediated bradycardia of the diving reflex. Atenolol, however, augmented the vagal bradycardia, presumably by sympathetic inhibition. In a dynamic bicycle ergometer test with a stepwise increasing work load, exercise performance was decreased by atenolol but not by quinapril. Inhibition of the renin-angiotensin system by quinapril was shown by a marked decrease in serum ACE activity and a several-fold increase in plasma renin activity (PRA). Atenolol produced a moderate reduction in PRA. Before or during exercise, plasma noradrenaline and adrenaline were not influenced by either drug. The results indicate that, unlike the atenolol-induced beta-adrenoceptor blockade, ACE inhibition by a single dose of quinapril had no clear effect on autonomic nervous function or exercise capacity.

The effects of rilmenidine and atenolol on mental stress, dynamic exercise and autonomic function in mild to moderate hypertension.

“…Overall, our findings in hypertensive patients support the view that both rilmenidine and atenolol attenuate sympathetic and enhance cardiac parasympathetic tone as previously shown in normotensive volunteers [10,26].…”

Atenolol blunts blood pressure increase during dynamic resistance exercise in hypertensives

“…The volunteers were blinded to the drug used in each experiment, and many adaptation sessions were conducted in both phases of the study. As the decreases in HR and BP observed in the study were similar to the ones previously described in the literature with randomized studies [33], the order of the experiments might have had minor effect on BP results.…”

“…To our knowledge, this is the first study to investigate the effects of a selective b1-adrenoceptor blocker on BP responses to dynamic resistance exercise. Previous studies have only evaluated the effects of atenolol on isometric resistance exercise [28][29][30][31][32][33][34] or the interaction between atenolol and atropine blockades on BP responses to dynamic resistance exercise [42]. In the present study, using only b-adrenoceptor blockade, we demonstrated that atenolol alone was able not only to decrease the absolute value of systolic BP but also to mitigate its increase during dynamic resistance exercise.…”

“…The effects of atenolol during aerobic exercise have been extensively studied, and it has been shown that β‐adrenoceptor blockade is able to reduce HR and BP maximum values, as well as their increase during aerobic activity [27]. Atenolol effects were also investigated during isometric resistance exercise, and it was shown that β‐adrenoceptor blockade decreases maximum BP values but does not affect the increase in BP [28–34]. This absence of effect is probably because an increase in systemic vascular resistance is the main mechanism for BP increase during isometric exercise [18, 35].…”