Effects of hypothermia and rewarming on phospholipase C-evoked glycerol output in rat myocardial cells.
The combined action of phosphatidylcholine preferring phospholipase C (PC-PLC) and intracellular lipases has recently been shown to cause glycerol output in energy deprived rat cardiomyocytes. In the present study we examined the effect of hypothermia and rewarming on PC-PLC evoked glycerol output in freshly isolated, calcium-tolerant myocytes. The cells were preincubated for 60 min at hypothermic (5 degrees C) or normothermic (37 degrees C) conditions in Krebs-Henseleit bicarbonate buffer (pH 7.4) supplemented with 1 mM DL-carnitine, 1% B.S.A. and 5 mM glucose. Addition of PC-PLC resulted in a significantly higher (P less than 0.05) output of glycerol in myocytes undergoing rewarming than in myocytes kept constantly at 5 degrees C or 37 degrees C. The values obtained for PC-PLC induced glycerol output (difference in glycerol output between incubations with and without PC-PLC) were 6.77 +/- 2.6 (37 degrees C), 4.54 +/- 1.7 (5 degrees C) and 22.85 +/- 5.9 (5-37 degrees C) nmol/10(6) cells.h. Rewarming in addition caused a significantly higher (P less than 0.05) leakage of lactate dehydrogenase (LDH) from the rewarmed cells as compared to cells at constant temperatures (5 degrees C or 37 degrees C). However, there was no additional effect of PC-PLC on LDH leakage. The elevated PC-PLC induced glycerol output in rewarmed myocytes was not related to a fall in the percentage of rod-shaped cells or a reduced cellular content of ATP, since no differences could be detected between the various myocyte preparations with respect to these parameters.(ABSTRACT TRUNCATED AT 250 WORDS)
Steigen
T K
TK
Department of Physiology, University of Tromsø, Norway.
Pettersen
S
S
Guddal
P H
PH
Larsen
T S
TS
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism*; D006706:Homeostasis / Q000502:physiology; D006358:Hot Temperature; D007035:Hypothermia / Q000378:metabolism*; D066298:In Vitro Techniques; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D010738:Type C Phospholipases / Q000502:physiology*
D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; D010738:Type C Phospholipases; D005990:Glycerol