In:
Canadian Journal of Physiology and Pharmacology, Canadian Science Publishing, Vol. 71, No. 10-11 ( 1993-10-01), p. 840-847
Abstract:
A phospholipase C specific for choline and ethanolamine acyl and plasmalogen glycerophospholipids (PC-PLC) has been described in myocardial tissue. In the present study we investigated whether an endogenous PC-PLC is activated in hypoxic, substrate-free incubations of rat ventricular myocytes. The phosphatidylcholine pool of the myocytes was prelabelled with [ 14 C]choline during a 4-h preincubation (pulse) period. The myocytes were subsequently washed and incubated for another 2 h (chase period) in normoxic, hypoxic, or hypoxic buffer supplemented with PC-PLC from Bacillus cereus. We hypothesized that an increase in the total (intracellular plus extracellular) content of [ 14 C]phosphocholine (one of the products resulting from PC-PLC action on phosphatidylcholine) throughout the chase period would indicate PC-PLC activity. Instead, an apparent decrease was observed for this parameter in all myocyte groups (17–29%), even in the one exposed to exogenous PC-PLC. However, 60 min after the start of the chase period, the level of total [ 14 C]phosphocholine was higher in hypoxic (p = 0.022) and hypoxic + PC-PLC exposed (p = 0.013) myocytes compared with normoxic controls. The total content of [ 14 C]choline increased significantly (p 〈 0.017) in all myocyte groups during the incubation period (98–153%) as a result of an increment of this metabolite in the buffer. Furthermore, the values measured in hypoxic and hypoxic + PC-PLC exposed myocytes during the first hour of the chase period were significantly (p 〈 0.017) higher than the corresponding values in normoxic myocytes. The present results do not allow firm conclusions regarding endogenous PC-PLC activation in energy-depleted rat cardiac myocytes. On the other hand, the data suggest activation of phosphocholine phosphatase or phospholipase D under these conditions.Key words: phosphatidylcholine, phospholipase C, phospholipase D, myocytes, hypoxia.
Type of Medium:
Online Resource
ISSN:
0008-4212
,
1205-7541
Language:
English
Publisher:
Canadian Science Publishing
Publication Date:
1993
detail.hit.zdb_id:
2004356-9
