Linked Life Data

2230708

Source:http://linkedlifedata.com/resource/pubmed/id/2230708

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1990-12-20
pubmed:abstractText
Singly dissected twitch fibers from frog muscle were studied on an optical bench apparatus after micro-injection with the pH indicator dye, phenol red. Dye-related absorbances in myoplasm, denoted by A0(lambda) and A90(lambda), were estimated as a function of wavelength lambda (450 nm less than or equal to lambda less than or equal to 640 nm) with light polarized parallel (0 degrees) and perpendicular (90 degrees) to the fiber axis respectively. At all lambda, A0(lambda) was slightly greater than A90(lambda), indicating that some of the phenol red molecules were bound to oriented structures accessible to myoplasm. The phenol red "isotropic" signal, [A0(lambda) + 2A90(lambda)]/3, a quantity equal to the average absorbance of all the dye molecules independent of their orientation, had a spectral shape that was red-shifted by approximately 10 nm in comparison with in vitro dye calibration curves measured in 140 mM KCl. The red-shifted spectrum also indicates that some phenol red molecules were bound in myoplasm. A quantitative estimate of indicator binding was obtained from measurements of the dye's apparent diffusion constant in myoplasm, denoted by Dapp. The small value of Dapp, 0.37 x 10(-6) cm2 s-1 (at 16 degrees C), can be explained if approximately 80% of the dye was bound to myoplasmic sites of low mobility. To estimate the apparent myoplasmic pH, denoted by pHapp, the isotropic absorbance of phenol red was fitted by in vitro calibration spectra. pHapp was found to be independent of dye concentration (0.2-2 mM), but varied widely (range, 6.8-7.5; mean value, 7.17) among fibers judged from functional characteristics to be normal. When fibers were subjected to acid or alkaline loads by exposure to Ringer's solution containing, respectively, dissolved CO2 or NH3, the changes in pHapp were in agreement with those expected from pH micro-electrode studies. It is concluded that in spite of the several indications for the presence of bound phenol red inside muscle cells, the pHapp signal from the indicator is useful for monitoring changes in myoplasmic pH in response to physiological and pharmacological manipulations.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0022-1295
pubmed:author
pubmed:issnType
Print
pubmed:volume
96
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
449-71
pubmed:dateRevised
2008-11-20
pubmed:meshHeading
pubmed:year
1990
pubmed:articleTitle
Absorbance signals from resting frog skeletal muscle fibers injected with the pH indicator dye, phenol red.
pubmed:affiliation
Department of Physiology, University of Pennsylvania Medical Center, Philadelphia 19104-6085.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't