Abstract
Introduction: Fasting has been shown to limit ischemic injury and improve functional activity after global ischemia. Because calcium overload is considered a mechanism of ischemic injury, we hypothesized that fasting would limit the accumulation of intracellular calcium [Ca]i during ischemia, potentially due to reduced accumulation of intracellular sodium [Na]i. Methods: To address this hypothesis, hearts isolated from rats fed either a normal diet or fasted for 24 hours underwent 20 min of global ischemia at 37°. In addition to functional parameters, [Na]i and [Ca]i were measured using 23Na and 19F spectroscopy using thulium-DOTP-5 and 5F-BAPTA, respectively. In vitro measurement of sarcoplasmic reticulum calcium uptake and release, as well as activity of the sarcolemmal Na-Ca exchanger, was performed in hearts from fed and fasted animals under baseline and ischemic conditions. Results: Hearts from fasted animals showed greater recovery of developed pressure (37 ± 9 vs. 11 ± 6 cm H2O, p < 0.05) and less contracture (end-diastolic pressure 25 ± 2 vs. 47 ± 2 cm H2O, p < 0.05) by the end of the reperfusion period. [Na]i was similar in the 2 groups during the first half of the ischemic period, albeit with a higher concentration of [Na]i in hearts from fed compared to fasted animals at reperfusion. Fasting markedly limited calcium accumulation during ischaemia, with end-ischemic calcium being 419 ± 46 nM in the hearts from fasted animals and 858 ± 140 nM in the hearts from fed animals (p < 0.01). There was no significant effect of fasting on calcium uptake or release by the SR, nor on sarcolemmal Na-Ca exchange activity. Conclusions: Fasting for 24 hours improves functional recovery and markedly limits [Ca]i accumulation during ischemia and early reperfusion. The mechanism for this phenomenon remains to be elucidated.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 463-470 |
| Number of pages | 8 |
| Journal | Basic Research in Cardiology |
| Volume | 96 |
| Issue number | 5 |
| DOIs | |
| State | Published - 2001 |
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Keywords
- 5F-BAPTA
- Calcium
- NMR spectroscopy
- Sodium
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine
Cite this
Fasting limits the increase in intracellular calcium during ischemia in isolated rat hearts. / Ramasamy, Ravichandran; Liu, Hong; Cherednichenko, Gennady; Schaefer, Saul.
In: Basic Research in Cardiology, Vol. 96, No. 5, 2001, p. 463-470.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Fasting limits the increase in intracellular calcium during ischemia in isolated rat hearts
AU - Ramasamy, Ravichandran
AU - Liu, Hong
AU - Cherednichenko, Gennady
AU - Schaefer, Saul
PY - 2001
Y1 - 2001
N2 - Introduction: Fasting has been shown to limit ischemic injury and improve functional activity after global ischemia. Because calcium overload is considered a mechanism of ischemic injury, we hypothesized that fasting would limit the accumulation of intracellular calcium [Ca]i during ischemia, potentially due to reduced accumulation of intracellular sodium [Na]i. Methods: To address this hypothesis, hearts isolated from rats fed either a normal diet or fasted for 24 hours underwent 20 min of global ischemia at 37°. In addition to functional parameters, [Na]i and [Ca]i were measured using 23Na and 19F spectroscopy using thulium-DOTP-5 and 5F-BAPTA, respectively. In vitro measurement of sarcoplasmic reticulum calcium uptake and release, as well as activity of the sarcolemmal Na-Ca exchanger, was performed in hearts from fed and fasted animals under baseline and ischemic conditions. Results: Hearts from fasted animals showed greater recovery of developed pressure (37 ± 9 vs. 11 ± 6 cm H2O, p < 0.05) and less contracture (end-diastolic pressure 25 ± 2 vs. 47 ± 2 cm H2O, p < 0.05) by the end of the reperfusion period. [Na]i was similar in the 2 groups during the first half of the ischemic period, albeit with a higher concentration of [Na]i in hearts from fed compared to fasted animals at reperfusion. Fasting markedly limited calcium accumulation during ischaemia, with end-ischemic calcium being 419 ± 46 nM in the hearts from fasted animals and 858 ± 140 nM in the hearts from fed animals (p < 0.01). There was no significant effect of fasting on calcium uptake or release by the SR, nor on sarcolemmal Na-Ca exchange activity. Conclusions: Fasting for 24 hours improves functional recovery and markedly limits [Ca]i accumulation during ischemia and early reperfusion. The mechanism for this phenomenon remains to be elucidated.
AB - Introduction: Fasting has been shown to limit ischemic injury and improve functional activity after global ischemia. Because calcium overload is considered a mechanism of ischemic injury, we hypothesized that fasting would limit the accumulation of intracellular calcium [Ca]i during ischemia, potentially due to reduced accumulation of intracellular sodium [Na]i. Methods: To address this hypothesis, hearts isolated from rats fed either a normal diet or fasted for 24 hours underwent 20 min of global ischemia at 37°. In addition to functional parameters, [Na]i and [Ca]i were measured using 23Na and 19F spectroscopy using thulium-DOTP-5 and 5F-BAPTA, respectively. In vitro measurement of sarcoplasmic reticulum calcium uptake and release, as well as activity of the sarcolemmal Na-Ca exchanger, was performed in hearts from fed and fasted animals under baseline and ischemic conditions. Results: Hearts from fasted animals showed greater recovery of developed pressure (37 ± 9 vs. 11 ± 6 cm H2O, p < 0.05) and less contracture (end-diastolic pressure 25 ± 2 vs. 47 ± 2 cm H2O, p < 0.05) by the end of the reperfusion period. [Na]i was similar in the 2 groups during the first half of the ischemic period, albeit with a higher concentration of [Na]i in hearts from fed compared to fasted animals at reperfusion. Fasting markedly limited calcium accumulation during ischaemia, with end-ischemic calcium being 419 ± 46 nM in the hearts from fasted animals and 858 ± 140 nM in the hearts from fed animals (p < 0.01). There was no significant effect of fasting on calcium uptake or release by the SR, nor on sarcolemmal Na-Ca exchange activity. Conclusions: Fasting for 24 hours improves functional recovery and markedly limits [Ca]i accumulation during ischemia and early reperfusion. The mechanism for this phenomenon remains to be elucidated.
KW - 5F-BAPTA
KW - Calcium
KW - NMR spectroscopy
KW - Sodium
UR - http://www.scopus.com/inward/record.url?scp=0035689525&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035689525&partnerID=8YFLogxK
U2 - 10.1007/s003950170028
DO - 10.1007/s003950170028
M3 - Article
C2 - 11605993
AN - SCOPUS:0035689525
VL - 96
SP - 463
EP - 470
JO - Basic Research in Cardiology
JF - Basic Research in Cardiology
SN - 0300-8428
IS - 5
ER -