Premium
Roles of Nitric Oxide and Prostaglandins in the Hyperemic Response to a Maximal Metabolic Stimulus: Redundancy Prevails
Author(s) -
Lopez Marcos G.,
Silva Bruno M.,
Walker Branton G.,
Joyner Michael J.,
Casey Darren P.
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.1056.12
Subject(s) - nitric oxide , stimulus (psychology) , chemistry , medicine , cardiology , endocrinology , psychology , cognitive psychology
We tested whether NO and prostaglandins (PG) contribute to the post hyperemic response to ischemic exercise (IE). Forearm blood flow (FBF) was measured with venous occlusion plethysmography following IE trials consisting of 5 min of ischemia and rhythmic handgrip exercise (final 2 minutes of ischemia). 17 subjects were randomized into 2 groups and performed 3 trials of IE during control (saline), N G ‐monomethyl‐L‐arginine (L‐NMMA; NOS inhibition) or ketorolac (cyclooxygenase inhibition) alone, and combined L‐NMMA/ketorolac infusion via a brachial arterial catheter. Peak and total (area under the curve; AUC) FBF and blood pressure (MAP) were measured for 3 min after each trial. Forearm vascular conductance (FVC) was calculated as FBF/MAP. No significant difference was detected between trials, regardless of drug order. For those receiving L‐NMMA first (n=8), total ΔFVC was 59.6±4.3, 57.8±6.0, and 59.9±5.6 ml·100ml −1 ·100mmHg −1 (p =0.82) for saline, L‐NMMA alone, and L‐NMMA+ketorolac infusions, respectively. For those receiving ketorolac first (n=9), total ΔFVC was 54.2±5.0, 56.9±4.5, and 56.5±5.3 ml·100ml −1 ·100mmHg −1 (p=0.69) for saline, ketorolac alone, and ketorlac+L‐NMMA infusions, respectively. These results suggest that NO and PGs are not obligatory for the post hyperemic response to ischemic exercise and that redundant vasodilator mechanisms predominate.