Linked Life Data

8118949

Source:http://linkedlifedata.com/resource/pubmed/id/8118949

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1994-4-6
pubmed:abstractText
The Ca2+ sensitivity of myofilaments was compared before and after skinning in the same rat trabeculae at a diastolic sarcomere length of 2.2 to 2.3 microns. Trabeculae from rat right ventricle were loaded with fura-2 salt by iontophoretic microinjection, and [Ca2+]i was determined from the epifluorescence at 510 nm when excited at 340 and 380 nm. Steady-state activation was achieved by stimulating the muscle at 10 Hz after 10 to 20 minutes of application of ryanodine (5 mumol/L). The muscles were then skinned with Triton X-100 (1%) for 15 to 25 minutes and subsequently activated with solutions containing varied [Ca2+]. The intact force-[Ca2+] relation was highly cooperative (Hill coefficient, 4.87 +/- 0.35; n = 10), with a low [Ca2+]i required for half-maximal activation (K1/2) (0.62 +/- 0.03 mumol/L). After skinning, the Hill coefficient fell to 2.72 and the K 1/2 shifted rightward to 2.2 mumol/L in the presence of 1.2 mmol/L free Mg2+. Because of uncertainty regarding the appropriate [Mg2+], we measured [Mg2+]i at 0.72 +/- 0.06 mmol/L (n = 11) with Mg-fura-2 salt. When activating solutions were modified to contain [Mg2+] = 0.5 mmol/L, the force-[Ca2+] relation was shifted to the left (K 1/2 = 0.93 +/- 0.1, n = 10) with a Hill coefficient of 3.75 +/- 0.37, but the changes were not sufficient to superimpose with the intact force-[Ca2+] relation (P < .05 versus intact). These results suggest that, despite the significant effect of Mg2+ on the force-[Ca2+] relation in skinned muscles, the Ca2+ responsiveness of the myofilaments is still altered by skinning.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0009-7330
pubmed:author
pubmed:issnType
Print
pubmed:volume
74
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
408-15
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Myofilament Ca2+ sensitivity in intact versus skinned rat ventricular muscle.
pubmed:affiliation
Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't