Linked Life Data

3254421

Source:http://linkedlifedata.com/resource/pubmed/id/3254421

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:dateCreated
1989-8-25
pubmed:abstractText
1. The mechanism of the rate-dependent decrease in intracellular pH (pHi) and its recovery were studied in isolated sheep cardiac Purkinje fibres. Intracellular Na+ activity (aiNa) and pHi were measured using ion-selective microelectrodes. Twitches were elicited by field stimulation or by depolarizing pulses applied using a two-microelectrode voltage clamp. 2. A 3 Hz train of short (50 ms) depolarizing voltage-clamp pulses induced a reversible fall in pHi which was accompanied by a reversible increase in aiNa. A train of longer (200 ms) pulses also produced a fall in pHi which was now paralleled by a decrease in aiNa. These observations indicate that the rate-dependent acidosis is not dependent upon a rise in aiNa. 3. Neither the fall in pHi nor the increase in aiNa seen upon an increase in action potential frequency was inhibited by amiloride (1 mmol l-1) which indicates that Na+-H+ exchange is not involved in the generation of the acidosis. Furthermore, the rate-dependent acidosis was not abolished in Na+-free solution (Li+ or N-methyl glucamine substituted) indicating that other Na+-requiring processes (such as Na+-Ca2+ exchange) are not a necessary requirement. Rate-dependent pHi changes were also unaffected by the stilbene compound DIDS indicating no participation by Cl--HCO-3 exchange. 4. The rate-dependent acidosis was inhibited by the organic calcium antagonist D600 (20 mumol l-1) which also inhibited twitch tension. This suggests that the acidosis is related to the activation by Ca2+ of developed tension. D600 also inhibited the rate-dependent rise in aiNa (field stimulation). 5. The rate-dependent acidosis was not inhibited by cyanide (2 mmol l-1) but it was blocked by iodoacetate (0.5 mmol l-1) and by 2-deoxyglucose (DOG) (10 mmol l-1, applied in glucose-free solution). These results suggest that the acidosis is generated metabolically via stimulation of glycolysis, following an increase in contraction. Contributions from aerobic metabolism are likely to be small. 6. Twitch tension was inhibited by ryanodine (10 mumol l-1) but the drug had little inhibitory effect on the rate-dependent acidosis. A tonic component of tension was observed, however, in the presence of ryanodine. The lack of effect of ryanodine upon the rate-induced acidosis is discussed. 7. The half-time of pHi recovery from the frequency-dependent acidosis was consistently shorter than that from an intracellular acid load induced by adding and then removing external NH4Cl (10 mmol l-1).(ABSTRACT TRUNCATED AT 400 WORDS)
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-13205, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-146205, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-2421940, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-2443659, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-2443663, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-2443691, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-2451001, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-25957, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-3392677, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-34042, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-3487074, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-3559998, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-3612086, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-3621056, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-3656122, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-3714459, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-3795073, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-3923187, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-3989725, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-4067571, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-4537130, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-599421, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-6325586, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-6614155, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-6631403, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-6823331, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-6875960, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-7012859, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-7099919, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-7310732, http://linkedlifedata.com/resource/pubmed/commentcorrection/3254421-7441547
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0022-3751
pubmed:author
pubmed:issnType
Print
pubmed:volume
406
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
483-501
pubmed:dateRevised
2009-11-18
pubmed:meshHeading
pubmed:year
1988
pubmed:articleTitle
Mechanism of rate-dependent pH changes in the sheep cardiac Purkinje fibre.
pubmed:affiliation
University of Laboratory of Physiology, Oxford.
pubmed:publicationType
Journal Article, In Vitro, Research Support, Non-U.S. Gov't