Alpha-adrenoceptor stimulation, lysophosphoglycerides, and lipid peroxidation in reoxygenation induced calcium uptake in rabbit myocardium.
Calcium uptake on reoxygenation of hypoxic cardiac muscle is well documented. Alpha-adrenoceptor stimulation by released catecholamines, lysophosphoglycerides and lipid peroxidation have all been suggested as mediators of this effect. We have measured the uptake of Ca2+ on reoxygenation in the isolated arterially perfused interventricular septum of the rabbit heart. The alpha agonist phenylephrine (1 mumol X litre-1) did not alter calcium uptake, and the presence of either prazosin (1 mumol X litre-1) or phentolamine (10 mumol X litre-1) did not alter the reoxygenation induced Ca2+ uptake. Lysophosphatidylcholine caused an increase in Ca2+ uptake above 8 mumol X litre-1 but also produced a simultaneous increase in the distribution volume of 51Cr-EDTA, an extracellular space marker, indicating loss of membrane integrity. Hydrogen peroxide and cumene hydroperoxide both caused an increased Ca2+ uptake, but no disruption of the cell membrane; the effect on Ca2+ uptake could be inhibited by Ni2+ ions. Alpha adrenergic stimulation and lysophosphoglycerides do not appear to be key to Ca2+ uptake on reoxygenation, but lipid peroxidation of the sarcolemma is a possible mechanism.
Tones
M A
MA
Poole-Wilson
P A
PA
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004195:Disease Models, Animal; D005994:Glycerophosphates / Q000378:metabolism*; D007511:Ischemia / Q000378:metabolism; D008054:Lipid Peroxides / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D011817:Rabbits; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D012508:Sarcolemma / Q000378:metabolism
D005994:Glycerophosphates; D008054:Lipid Peroxides; D011942:Receptors, Adrenergic, alpha; D010100:Oxygen; D002118:Calcium