Document Detail

Myocardial contractility recovery during hypercapnic acidosis: its dissociation from recovery in pHi by ryanodine.
MedLine Citation:
PMID:  7656191     Owner:  NLM     Status:  MEDLINE    
Myocardial contractility falls quickly during respiratory acidosis but if acidosis is maintained a slow gradual return towards control state is detected. In cat papillary muscle, changes in developed tension (DT) during isometric contractions (pacing rate 0.2 Hz) and intracellular pH (pHi) were continuously monitored before and during hypercapnia to study the contribution of pHi recovery to the recovery of contractility. On exposure to hypercapnia (extracellular pH [pHo] = 6.90) DT fell to 50.33 +/- 2.20% of control and pHi decreased from 7.21 +/- 0.05 to 6.90 +/- 0.02. After 30 mins of hypercapnia DT recovered to 64.66 +/- 4.05% of control, but no significant recovery in pHi was detected. Intracellular sodium concentration slowly rose to 61.05 +/- 23.79% over basal level 10 mins after the onset of hypercapnia and it remained elevated for 10 mins before gradually returning to control levels. When pHo was kept at 7.40 during hypercapnia by increasing sodium bicarbonate concentration, DT recovered to 79.11 +/- 6.94% of control after 30 mins of hypercapnia, while a significant recovery of pHi (0.12 +/- 0.02 pH units) was detected. Low extracellular sodium concentration diminished contractility recovery during hypercapnia without changing the initial decrease in DT. 5-[N-ethyl-N-isopropyl] amiloride (EIPA) (5 microM) increased the initial fall in DT to 34.33 +/- 8.68% of control and abolished the recovery. Sarcoplasmic reticulum (SR) inhibition by ryanodine (0.5 microM) markedly reduced the recovery of contractility without altering the recovery in pHi.(ABSTRACT TRUNCATED AT 250 WORDS)
N G Pérez; A R Mattiazzi; M C Camilion de Hurtado; H E Cingolani
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Canadian journal of cardiology     Volume:  11     ISSN:  0828-282X     ISO Abbreviation:  Can J Cardiol     Publication Date:    1995 Jul-Aug
Date Detail:
Created Date:  1995-10-03     Completed Date:  1995-10-03     Revised Date:  2008-04-09    
Medline Journal Info:
Nlm Unique ID:  8510280     Medline TA:  Can J Cardiol     Country:  CANADA    
Other Details:
Languages:  eng     Pagination:  553-60     Citation Subset:  IM; S    
Centro de Investigaciones Cardiovasculares, Facultade de Ciencias Medicas de La Plata, Argentina.
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MeSH Terms
Acidosis, Respiratory / physiopathology*
Cardiac Pacing, Artificial
Hydrogen-Ion Concentration
Hypercapnia / physiopathology*
Myocardial Contraction*
Papillary Muscles
Ryanodine / pharmacology*
Sarcoplasmic Reticulum / drug effects*
Sodium / metabolism
Reg. No./Substance:
15662-33-6/Ryanodine; 7440-23-5/Sodium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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