Mechanisms responsible for cell volume regulation during hyperkalemic cardioplegic arrest.
BACKGROUND
Cardioplegia has been shown to induce significant cell swelling. This study tested the hypothesis that (1) the [K+][Cl-] product of the cardioplegia solution is the main determinant of myocyte swelling, and (2) reperfusion myocyte shrinkage results from a rectifying Cl- conductance.


METHODS
Rabbit ventricular myocytes were superfused with 37 degrees C Krebs-Henseleit solution for 10 minutes. Then cells underwent 20 minutes of superfusion with standard St. Thomas' solution ([K+][Cl-] product = 2566 mmol/L2) and two solutions with lower [K+][Cl-] product (1500 and 700 mmol/L2) at 9 degrees C. Cells were then resuperfused with 37 degrees C Krebs-Henseleit solution for 30 minutes. Cell volume was measured by videomicroscopy.


RESULTS
Cells superfused with St. Thomas' having [K+][Cl-] products of 2,566, 1,500, and 700 mmol/L2 swelled by 9.18%+/-3.57%, 5.51%+/-1.08%, and 1.49%+/-1.56%, respectively. Reexposure to Krebs-Henseleit solution caused these cells to shrink by 5.79%+/-1.41%, 8.72% +/-3.68%, and 13.46%+/-5.60%, respectively. This shrinkage was blocked by Cl- channel blockers given at the onset of superfusion.


CONCLUSIONS
Lowering the [K+][Cl-] product of St. Thomas' solution attenuated myocyte edema. Myocyte shrinkage during reexposure to Krebs-Henseleit solution resulted from the volume-activated Cl- channel.
Sun
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Division of Cardiothoracic and Vascular Surgery, The Milton S. Hershey Medical Center, Penn State University, Hershey, Pennsylvania, USA.
Ducko
C T
CT
Hoenicke
E M
EM
Reigle
K
K
Damiano
R J
RJ
D000818:Animals; D001639:Bicarbonates / Q000737:chemistry / Q000494:pharmacology; D002122:Calcium Chloride / Q000737:chemistry / Q000494:pharmacology; D002314:Cardioplegic Solutions / Q000737:chemistry / Q000494:pharmacology*; D048429:Cell Size / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005947:Glucose / Q000737:chemistry / Q000494:pharmacology; D006324:Heart Arrest, Induced; D008274:Magnesium / Q000737:chemistry / Q000494:pharmacology; D008297:Male; D009206:Myocardium / Q000166:cytology*; D011189:Potassium Chloride / Q000032:analysis / Q000737:chemistry / Q000494:pharmacology; D011817:Rabbits; D012965:Sodium Chloride / Q000737:chemistry / Q000494:pharmacology; D014325:Tromethamine / Q000737:chemistry / Q000494:pharmacology
D001639:Bicarbonates; D002314:Cardioplegic Solutions; C074097:Krebs-Henseleit solution; C041711:St. Thomas' Hospital cardioplegic solution; D014325:Tromethamine; D012965:Sodium Chloride; D011189:Potassium Chloride; D008274:Magnesium; D005947:Glucose; D002122:Calcium Chloride