dc.contributor.author	Spangenburg, Espen E.	en
dc.contributor.committeechair	Williams, Jay H.	en
dc.contributor.committeemember	Ward, Christopher W.	en
dc.contributor.committeemember	Moore, David M.	en
dc.contributor.department	Human Nutrition, Foods, and Exercise	en
dc.date.accessioned	2014-03-14T20:22:14Z	en
dc.date.adate	1997-04-24	en
dc.date.available	2014-03-14T20:22:14Z	en
dc.date.issued	1997-04-24	en
dc.date.rdate	1998-04-24	en
dc.date.sdate	1998-07-25	en
dc.description.abstract	Numerous studies have attributed the decrease in force production of skeletal muscle during exercise to a increase in lactate concentration ([lactate]). This notion is based on the high negative correlation between plasma lactate and force during fatigue and recovery. These experiments attempted to determine if lactate directly effects force production in skeletal muscle. Mouse extensor digitorum longus muscles (EDL) were isolated and incubated in a buffered Ringers solution at a pH 7.2 and exposed at three minute intervals to a final concentration of 10, 20, 30, 50mM lactate. At 21° C, tetanic force production (Po, 250ms, 110Hz) decreased to 99.3 ± 1.0, 97.1 ± 1.2, 94.9 ± 1.1* and 93.1 ± 1.3% of initial and the rate of force development (+dP/dt) was reduced to 99.4 ± 0.7, 96.8 ± 0.5, 93.5 ± 0.6, and 89.3 ± 1.2% of initial (p<0.05 vs untreated muscles). At 37° C the effects of lactate were augmented. Po was reduced to 89.7 ± 1.1, 81.0 ± 2.4, 73 ± 3.9, and 61.6 ± 5.4% and +dP/dt was reduced to 79.4 ± 1.8, 65.9 ± 2.8, 55.4 ± 4.0, and 44.3 ± 5.0% of initial (*p<0.05 vs control muscles). The next phase was to determine if the changes in Po and +dP/dt were due to alterations in the sacroplasmic reticulum (SR) Ca2+ exchange. The SR of EDL homogenates were actively loaded with Ca2+ and release was initiated by 25 mM AgNO3. The rate of Ca2+ release was significantly reduced by 31% (2.48 ± 1.21 vs 1.72 ± 0.24 mmol·mg-1·min-1) in the presence of 25 mM lactate. These results indicate that exposure to increased [lactate], independent of the H+, decreases force production of whole muscle, effects that are greater at 37° C than 21° C. Also increased lactate reduces the rate of SR Ca2+ release. These results suggest that lactate depresses whole muscle force production by altering Ca2+ release of the SR. They also support the idea that increased lactate concentrations disrupt normal muscle function leading to the development of fatigue.	en
dc.description.degree	Master of Science	en
dc.identifier.other	etd-582914849741271	en
dc.identifier.sourceurl	http://scholar.lib.vt.edu/theses/available/etd-582914849741271/	en
dc.identifier.uri	http://hdl.handle.net/10919/30615	en
dc.publisher	Virginia Tech	en
dc.relation.haspart	EES1A.PDF	en
dc.relation.haspart	EES1.PDF	en
dc.relation.haspart	EES2.PDF	en
dc.relation.haspart	EES3.PDF	en
dc.relation.haspart	EES4.PDF	en
dc.relation.haspart	EES5.PDF	en
dc.rights	In Copyright	en
dc.rights.uri	http://rightsstatements.org/vocab/InC/1.0/	en
dc.subject	sarcoplasmic retciulum	en
dc.subject	Fatigue	en
dc.subject	calcium	en
dc.subject	muscle	en
dc.subject	lactate	en
dc.title	The Effects of Lactate on Whole Muscle Function and Sarcoplasmic Reticulum Function	en
dc.type	Thesis	en
thesis.degree.discipline	Human Nutrition, Foods, and Exercise	en
thesis.degree.grantor	Virginia Polytechnic Institute and State University	en
thesis.degree.level	masters	en
thesis.degree.name	Master of Science	en

The Effects of Lactate on Whole Muscle Function and Sarcoplasmic Reticulum Function

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