Linked Life Data

8387071

Source:http://linkedlifedata.com/resource/pubmed/id/8387071

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1993-6-1
pubmed:abstractText
This study examined the dose-response effects of caffeine on plasma K+ balance during prolonged exercise. Two series of experiments were performed. In series A, 1 h after ingestion of 9 mg/kg dextrose (placebo) or 9 mg/kg caffeine, eight subjects cycled at 78% of peak O2 consumption until exhaustion; in series B, in four trials, 1 h after ingestion of 0, 3, 6, or 9 mg/kg caffeine, eight subjects ran on a treadmill at 85% of peak O2 consumption until exhaustion. Blood was sampled from an antecubital vein for analysis of hematocrit, plasma concentrations of epinephrine ([Epi]) and norepinephrine, and [K+]. The change in plasma volume was calculated from hematocrit. During exercise, there was a net addition of K+ to and a net loss of fluid from the plasma compartment. Caffeine had no effect on plasma volume and norepinephrine concentration during exercise. In series A and B 9 mg/kg caffeine and in series B 6 mg/kg caffeine resulted in a significant attenuation of the increase in plasma [K+] with exercise. In series A increases in plasma [Epi] were 1.4- to 2-fold greater during exercise with caffeine than with placebo. At exhaustion, plasma [Epi] was twofold higher with caffeine (10.1 +/- 2.3 nM) than with placebo (5.3 +/- 0.8 nM), whereas plasma [K+] was only 4.88 +/- 0.18 meq/l with caffeine compared with 5.37 +/- 0.14 meq/l with placebo. It is concluded that caffeine attenuates the increase in plasma [K+] during exercise by stimulation (via one of its metabolites or by increased [Epi]) of tissue Na-K pump activity.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
8750-7587
pubmed:author
pubmed:issnType
Print
pubmed:volume
74
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1149-55
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Caffeine attenuates the exercise-induced increase in plasma [K+] in humans.
pubmed:affiliation
School of Human Biology, University of Guelph, Ontario, Canada.
pubmed:publicationType
Journal Article, Clinical Trial, Controlled Clinical Trial, Research Support, Non-U.S. Gov't