Developmental changes in the effects of pH on contraction and Ca2+ current in rabbit heart
Protons inhibit Ca2+ current and contraction in heart muscle. The present study compares the effects of lowering the pH of the bath solution on single-cell contraction, action potential configuration and Ca2+ currents between neonatal and adult rabbit hearts. We found that a reduction of extracellular pH from 7.3 to 6.3 decreased cell contraction amplitude to 84.3% of control in isolated neonatal myocytes. A comparable change in extracellular pH resulted in a decrease in cell contraction to 56.2% of control in adult cells. Similarly, tension generation in intact neonatal papillary muscles was less sensitive to a decrease in external pH as compared to papillary muscles from adult animals. In addition, acidosis caused a less pronounced inhibition of Ca2+ current in neonatal cells than in adult cells (85 +/- 4% nu 62 +/- 4% of control, pH = 6.3, P < 0.001; 63 +/- 5% nu 32 +/- 5% of control, pH = 5.8, P < 0.001). Thus, the effect of external acidosis on myocardial contractility is commensurate with the effect on trans-sarcolemmal Ca2+ current. The membrane potential at which peak Ca2+ current occurred was not altered by low pH in neonatal cells but was shifted toward positive potentials by 17.7 mV in adult myocytes. Further, low external pH solution reduced Ca2+ current conductance more in adult cells than in neonatal cells. Moreover, action potential configuration in neonatal cells was altered less by acidosis as compared with adult cells. These findings may help explain the greater resistance of neonatal hearts to extracellular acidosis.
| Medienart: |
Artikel |
|---|
| Erscheinungsjahr: |
1996 |
|---|---|
| Erschienen: |
1996 |
| Enthalten in: |
Zur Gesamtaufnahme - volume:28 |
|---|---|
| Enthalten in: |
Journal of molecular and cellular cardiology - 28(1996), 3 vom: 15. März, Seite 635-42 |
| Sprache: |
Englisch |
|---|
| Beteiligte Personen: |
Chen, F [VerfasserIn] |
|---|
| Themen: |
Calcium |
|---|
| Anmerkungen: |
Date Completed 05.02.1997 Date Revised 20.11.2014 published: Print Citation Status MEDLINE |
|---|
| Förderinstitution / Projekttitel: |
|
|---|
| PPN (Katalog-ID): |
NLM089770307 |
|---|
| LEADER | 01000naa a22002652 4500 | ||
|---|---|---|---|
| 001 | NLM089770307 | ||
| 003 | DE-627 | ||
| 005 | 20231222080735.0 | ||
| 007 | tu | ||
| 008 | 231222s1996 xx ||||| 00| ||eng c | ||
| 028 | 5 | 2 | |a pubmed24n0300.xml |
| 035 | |a (DE-627)NLM089770307 | ||
| 035 | |a (NLM)9011646 | ||
| 040 | |a DE-627 |b ger |c DE-627 |e rakwb | ||
| 041 | |a eng | ||
| 100 | 1 | |a Chen, F |e verfasserin |4 aut | |
| 245 | 1 | 0 | |a Developmental changes in the effects of pH on contraction and Ca2+ current in rabbit heart |
| 264 | 1 | |c 1996 | |
| 336 | |a Text |b txt |2 rdacontent | ||
| 337 | |a ohne Hilfsmittel zu benutzen |b n |2 rdamedia | ||
| 338 | |a Band |b nc |2 rdacarrier | ||
| 500 | |a Date Completed 05.02.1997 | ||
| 500 | |a Date Revised 20.11.2014 | ||
| 500 | |a published: Print | ||
| 500 | |a Citation Status MEDLINE | ||
| 520 | |a Protons inhibit Ca2+ current and contraction in heart muscle. The present study compares the effects of lowering the pH of the bath solution on single-cell contraction, action potential configuration and Ca2+ currents between neonatal and adult rabbit hearts. We found that a reduction of extracellular pH from 7.3 to 6.3 decreased cell contraction amplitude to 84.3% of control in isolated neonatal myocytes. A comparable change in extracellular pH resulted in a decrease in cell contraction to 56.2% of control in adult cells. Similarly, tension generation in intact neonatal papillary muscles was less sensitive to a decrease in external pH as compared to papillary muscles from adult animals. In addition, acidosis caused a less pronounced inhibition of Ca2+ current in neonatal cells than in adult cells (85 +/- 4% nu 62 +/- 4% of control, pH = 6.3, P < 0.001; 63 +/- 5% nu 32 +/- 5% of control, pH = 5.8, P < 0.001). Thus, the effect of external acidosis on myocardial contractility is commensurate with the effect on trans-sarcolemmal Ca2+ current. The membrane potential at which peak Ca2+ current occurred was not altered by low pH in neonatal cells but was shifted toward positive potentials by 17.7 mV in adult myocytes. Further, low external pH solution reduced Ca2+ current conductance more in adult cells than in neonatal cells. Moreover, action potential configuration in neonatal cells was altered less by acidosis as compared with adult cells. These findings may help explain the greater resistance of neonatal hearts to extracellular acidosis | ||
| 650 | 4 | |a Journal Article | |
| 650 | 4 | |a Research Support, Non-U.S. Gov't | |
| 650 | 4 | |a Research Support, U.S. Gov't, P.H.S. | |
| 650 | 7 | |a Calcium |2 NLM | |
| 650 | 7 | |a SY7Q814VUP |2 NLM | |
| 700 | 1 | |a Wetzel, G T |e verfasserin |4 aut | |
| 700 | 1 | |a Friedman, W F |e verfasserin |4 aut | |
| 700 | 1 | |a Klitzner, T S |e verfasserin |4 aut | |
| 773 | 0 | 8 | |i Enthalten in |t Journal of molecular and cellular cardiology |d 1970 |g 28(1996), 3 vom: 15. März, Seite 635-42 |w (DE-627)NLM00001964X |x 1095-8584 |7 nnns |
| 773 | 1 | 8 | |g volume:28 |g year:1996 |g number:3 |g day:15 |g month:03 |g pages:635-42 |
| 912 | |a GBV_USEFLAG_A | ||
| 912 | |a GBV_NLM | ||
| 951 | |a AR | ||
| 952 | |d 28 |j 1996 |e 3 |b 15 |c 03 |h 635-42 | ||