Abstract
This study was designed to examine the effects of hypoxia, acidosis, glucose-free medium and their combination on contraction and sarcoplasmic reticulum (SR) function in rat ventricular trabeculae. The isometric twitch tension was measured during superfusion with hypoxic (PO2 < 30 mmHg), acidic (pH 6.80), glucose-free, or their combined ("ischemic") Tyrode's solution at 20°C. The time needed to fully recover the contraction induced by 10 mm caffeine (repriming time) was measured to indirectly estimate the Ca2+ uptake of the SR. In "ischemia" and acidosis, the peak developed tension decreased progressively for the first 30 min (37.6 ± 9.2% and 56.6 ± 8.4% of control at 30 min, respectively), and then became steady. In hypoxic solution, the peak developed tension decreased moderately for the first 30 min (86.8 ± 4.8% of control at 30 min), and thereafter remained steady. Developed tension did not change significantly during 60 min of superfusion with glucose-free solution. The repriming time of caffeine contraction was significantly delayed in both "ischemic" and hypoxic solutions, but was unchanged in acidic and glucose-free solutions. These results lead us to suggest that depressed SR function to accumulate Ca2+ may contribute to the decline in tension in ischemia and hypoxia, but that other mechanisms are important in the tension decline induced by acidosis.
| Original language | English |
|---|---|
| Pages (from-to) | 697-705 |
| Number of pages | 9 |
| Journal | Journal of Molecular and Cellular Cardiology |
| Volume | 22 |
| Issue number | 6 |
| DOIs | |
| State | Published - Jan 1 1990 |
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Keywords
- Acidosis
- Caifeine
- Contractile function
- Hypoxia
- Sarcoplasmic reticulum
ASJC Scopus subject areas
- Molecular Biology
- Cardiology and Cardiovascular Medicine
Cite this
Effects of hypoxia, acidosis, and simulated ischemia on repriming of caffeine contracture in rat myocardium. / Shimizu, Motoyoshi; Kimura, Shinichi; Myerburg, Robert J; Bassett, Arthur L.
In: Journal of Molecular and Cellular Cardiology, Vol. 22, No. 6, 01.01.1990, p. 697-705.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Effects of hypoxia, acidosis, and simulated ischemia on repriming of caffeine contracture in rat myocardium
AU - Shimizu, Motoyoshi
AU - Kimura, Shinichi
AU - Myerburg, Robert J
AU - Bassett, Arthur L.
PY - 1990/1/1
Y1 - 1990/1/1
N2 - This study was designed to examine the effects of hypoxia, acidosis, glucose-free medium and their combination on contraction and sarcoplasmic reticulum (SR) function in rat ventricular trabeculae. The isometric twitch tension was measured during superfusion with hypoxic (PO2 < 30 mmHg), acidic (pH 6.80), glucose-free, or their combined ("ischemic") Tyrode's solution at 20°C. The time needed to fully recover the contraction induced by 10 mm caffeine (repriming time) was measured to indirectly estimate the Ca2+ uptake of the SR. In "ischemia" and acidosis, the peak developed tension decreased progressively for the first 30 min (37.6 ± 9.2% and 56.6 ± 8.4% of control at 30 min, respectively), and then became steady. In hypoxic solution, the peak developed tension decreased moderately for the first 30 min (86.8 ± 4.8% of control at 30 min), and thereafter remained steady. Developed tension did not change significantly during 60 min of superfusion with glucose-free solution. The repriming time of caffeine contraction was significantly delayed in both "ischemic" and hypoxic solutions, but was unchanged in acidic and glucose-free solutions. These results lead us to suggest that depressed SR function to accumulate Ca2+ may contribute to the decline in tension in ischemia and hypoxia, but that other mechanisms are important in the tension decline induced by acidosis.
AB - This study was designed to examine the effects of hypoxia, acidosis, glucose-free medium and their combination on contraction and sarcoplasmic reticulum (SR) function in rat ventricular trabeculae. The isometric twitch tension was measured during superfusion with hypoxic (PO2 < 30 mmHg), acidic (pH 6.80), glucose-free, or their combined ("ischemic") Tyrode's solution at 20°C. The time needed to fully recover the contraction induced by 10 mm caffeine (repriming time) was measured to indirectly estimate the Ca2+ uptake of the SR. In "ischemia" and acidosis, the peak developed tension decreased progressively for the first 30 min (37.6 ± 9.2% and 56.6 ± 8.4% of control at 30 min, respectively), and then became steady. In hypoxic solution, the peak developed tension decreased moderately for the first 30 min (86.8 ± 4.8% of control at 30 min), and thereafter remained steady. Developed tension did not change significantly during 60 min of superfusion with glucose-free solution. The repriming time of caffeine contraction was significantly delayed in both "ischemic" and hypoxic solutions, but was unchanged in acidic and glucose-free solutions. These results lead us to suggest that depressed SR function to accumulate Ca2+ may contribute to the decline in tension in ischemia and hypoxia, but that other mechanisms are important in the tension decline induced by acidosis.
KW - Acidosis
KW - Caifeine
KW - Contractile function
KW - Hypoxia
KW - Sarcoplasmic reticulum
UR - http://www.scopus.com/inward/record.url?scp=0025124866&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0025124866&partnerID=8YFLogxK
U2 - 10.1016/0022-2828(90)91012-V
DO - 10.1016/0022-2828(90)91012-V
M3 - Article
C2 - 2231737
AN - SCOPUS:0025124866
VL - 22
SP - 697
EP - 705
JO - Journal of Molecular and Cellular Cardiology
JF - Journal of Molecular and Cellular Cardiology
SN - 0022-2828
IS - 6
ER -