Hyperoxic exercise attenuates post-exercise vasodilatation independent of reduced NO (New et al, 2008) but coincident with a diminished bioavailability of atrial natriuretic peptide (New et al, 2009). The present study investigated the influence of adrenaline (AD) and nor-adrenaline (NA) on post-exercise haemodynamics. 9 males, mean arterial pressure (MAP) = 106 ± 5 mmHg (50 ± 10 yr), not on medication, were studied following 30-minutes of cycle exercise at 70% maximal oxygen consumption in hyperoxia (50% O2) and normoxia (21% O2). Subjects were followed post-exercise for 2-hours. Left ventricular haemodynamics were assessed via echocardiography and systemic vascular resistance (SVR)/vascular conductance determined by the quotient of MAP/Q and Q/MAP, respectively. Peripheral venous blood was sampled from an antecubital vein pre-, immediately post-, 1-hour post- (P1) and 2-hours post- (P2) exercise and metabolite concentrations corrected for plasma volume shifts. AD and NA were determined via reverse-phase high-performance liquid chromatograpy using electrochemical detection. Data were analysed with a two-way repeated measures ANOVA and post-hoc Bonferroni-corrected paired samples T-tests. Hyperoxic exercise blunted post-exercise haemodynamics by attenuating the reductions (from normoxic baseline) in SVR (21 ± 20.7 vs. 38 ± 19.3 %, 11 ± 8.2 vs. 19 ± 5.5 % and 11 ± 8.9 vs. 15 ± 9.6%, P<0.05 vs. normoxic exercise at post, P1 and P2 respectively) and MAP (3 ± 4 [elevation] vs. 0.5 ± 5 mmHg, 3 ± 3 vs. 6 ± 4 mmHg, 3 ± 3 vs. 4 ± 3 mmHg, P<0.05 vs. normoxic exercise at post, P1 and P2 respectively) (Paired samples T-tests). AD and NA concentrations were invariant between conditions P>0.05, Paired samples T-tests; Table 1). These results indicate that an augmented adrenergic response is not a principle governor of the attenuated vasodilatation. Whether changes in alpha- or beta-receptor sensitivity play a role requires further investigation, although, it appears that the deleterious influence of hyperoxia on post-exercise haemodynamics has non-adrenergic origins.
|Statws||Cyhoeddwyd - 2009|
|Digwyddiad||Physiology 2009 - Dublin, Iwerddon|
Hyd: 6 Gorff 2009 → …
|Cyfnod||6/07/09 → …|