Document Detail


Sildenafil Improves Microvascular O2 Delivery-to-Utilization Matching and Accelerates Exercise O2 Uptake Kinetics in Chronic Heart Failure.
MedLine Citation:
PMID:  23023868     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Nitric oxide (NO) can temporally and spatially match microvascular O(2) delivery (Q'O(2mv)) to O(2) uptake (V'O(2)) in the skeletal muscle, a crucial adjustment to exercise tolerance that is impaired in chronic heart failure (CHF). In order to investigate the effects of NO bioavailability induced by sildenafil intake on muscle Q'O(2mv)-to-O(2) utilization matching and V'O(2) kinetics 10 males with CHF (ejection fraction= 27 ± 6 %) undertook constant work rate exercise (70-80 % peak). Breath-by-breath V'O(2), fractional O(2) extraction in the vastus lateralis (~ [deoxy-Hb+Mb] by near infrared spectroscopy), and cardiac output were evaluated after sildenafil (50 mg) or placebo. Sildenafil increased exercise tolerance compared to placebo by ~ 20 %, an effect that was related to faster on- and off-exercise V'O(2) kinetics (p<0.05). Active treatment, however, failed to accelerate cardiac output dynamics (p>0.05). On-exercise [deoxy-Hb+Mb] kinetics were slowed by sildenafil (~ 25 %) with a subsequent response "overshoot", N= 8) being significantly lessened or even abolished. In contrast, [deoxy-Hb+Mb] recovery was faster with sildenafil (~ 15 %). Improvements in muscle oxygenation with sildenafil were related to faster on-exercise V'O(2) kinetics, blunted oscillations in ventilation (N= 9), and greater endurance exercise capacity (p<0.05). Sildenafil intake enhanced intramuscular Q'O(2mv)-to-O(2) matching with beneficial effects on V'O(2) kinetics and exercise capacity in CHF. The lack of effect on cardiac output suggests that improvement in blood flow to and within skeletal muscles underlies these effects.
Authors:
Priscila A Sperandio; Mayron F Oliveira; Miguel K Rodrigues; Danilo C Berton; Erika Treptow; Luiz E Nery; Dirceu R Almeida; J Alberto Neder
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-9-28
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  -     ISSN:  1522-1539     ISO Abbreviation:  Am. J. Physiol. Heart Circ. Physiol.     Publication Date:  2012 Sep 
Date Detail:
Created Date:  2012-10-1     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
1Federal University of Sao Paulo.
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