Adenosine receptor antagonist and augmented vasodilation during hypoxic exercise. Journal of applied physiology (Bethesda, Md. : 1985) [J Appl Physiol] Journal article | | Title | Adenosine receptor antagonist and augmented vasodilation during hypoxic exercise. | | Author(s) | Casey DP, Madery BD, Pike TL, Eisenach JH, Dietz NM, Joyner MJ, Wilkins BW | | Institution | Mayo Clinic. | | Source | J Appl Physiol 2009 Aug 6. | | Abstract | We tested the hypothesis that adenosine contributes to augmented skeletal muscle vasodilation during hypoxic exercise. In separate protocols subjects performed incremental rhythmic forearm exercise (10% and 20% of maximum) during normoxia and normocapnic hypoxia (80% arterial O2 saturation). In protocol 1 (n = 8), subjects received intra-arterial administration of saline (control) and aminophylline (adenosine receptor antagonist). In protocol 2 (n = 10), subjects received intra-arterial phentolamine (alpha-adrenoceptor antagonist) and combined phentolamine/aminophylline administration. Forearm vascular conductance (FVC; ml min(-1) (100mmHg)(-1) was calculated from forearm blood flow (ml min(-1)) and blood pressure (mmHg). In protocol 1, the change in FVC (Delta from normoxic baseline) during hypoxic exercise with saline was 172 +/- 29 and 314 +/- 34 ml min(-1) (100 mmHg)(-1) (10% and 20% respectively). Aminophylline administration did not affect DeltaFVC during hypoxic exercise at 10% (190 +/- 29 ml min(-1) (100 mmHg)(-1); P = 0.4) or 20% (287 +/- 48 ml min(-1) (100 mmHg)(-1); P = 0.3). In protocol 2, the DeltaFVC due to hypoxic exercise with phentolamine infusion was 313 +/- 30 and 453 +/- 41 (10% and 20% respectively). DeltaFVC was similar at 10% (352 +/- 39 ml min(-1) (100 mmHg)(-1); P = 0.8) and 20% (528 +/- 45 ml min(-1) (100 mmHg)-1; P = 0.2) hypoxic exercise with combined phentolamine/aminophylline. In contrast, DeltaFVC to exogenous adenosine was reduced by aminophylline administration in both protocols (P < 0.05 for both). These observations suggest that adenosine receptor activation is not obligatory for the augmented hyperemia during hypoxic exercise in humans. Key words: aminophylline, systemic hypoxia, muscle blood flow. | | Language | ENG | | Pub Type(s) | JOURNAL ARTICLE
| | PubMed ID | 19661449 |
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