some professors said, that the primary cells get the total different oxygen content during the isolation and culture, to the biological requirement like the heard in the body. The primary cells get always too much oxygen and is critical used for the hypoxia-reoxygenation.
you can use whatever is suitable for your own studies, depending on the question you ask and tools available. there are hundreds (if not thousands) publications on I/R using both types of cells. generally speaking, primary cells would be more "physiological" model and they are more "oxphos" as people say nowadays.
regarding growing cells at ambient air and how it is affecting all oxygen metabolism - this is very old but still usually neglected problem. in situ (say cardiac tissue ) concentration of O2 is definitely _at least_ one order of magnitude less, right? but we still grow cells at 20% O2.
third - I do not see a problem of making an apparatus able to support whatever O2 level from 100 to 0% - they can be made in house or available from several manufacturers.
There are many issues behind this question. Freshly isolated cells relieve from a recent enzymatic and calcium challenges. It is not the best material for several hour duration ischemic protocol. These cells may be suitable for physiological investigation, but the amount of viable cells may be a limit for biochemical assays. In addition, it must be remind that acidosis is protective and thus delay, if not blocks, cell injury. Moreover, increasing K+ stop cell beatings, which is not desirable for functional recording.
Also very different if neonatal or adult cells. 100s of papers on cardiomyocyte I/R and H/R with different protocols, as mentioned above depends on goal. Even a media change of myocytes transiently activates p38.
Indeed, development stage of the cell of origin is a key question and often misinterpreted. Freshly isolated adult cardiomyocytes display differentiated electrical properties (althgough under imposed resting potentialand during quite short term protocol), but they dedifferentiate in culture conditions. Neonatal cardiomyocytes, in appropriate culture condition, develop adult like electrical function, characterizd by fast sodium channels (which is a KEY MARKER in the sequence of response to ischemia). Evaluation of ischemia-induced dysfunction based on contration only is UNSUFFICIENT, since beatings stop before action potential changes.
I would recommend to use a hypoxia chamber. In order to achieve the pO2 you wish to expose your cells to (at least one order of magnitude lower than room air if you want to study your cells at approximately physiological conditions, in which case you should also ajust pCO2) monitor pO2 (e.g. by quenching optodes or by Clark-type electrodes) in the immediate vicinity of your cells (i.e. within the culture medium = the fluid phase) and adjust the chamber's gas phase pO2 until you reach your desired pO2. Note that because of the diffusion taking place within the fluid phase, there is a certain time lag between gas phase pO2 and that in the vicinity of your cells.
As said Erdmann above, you have to check the actual PO2 achieved close to the cells. Second, PCO2 and pH must stay normal (add CO2 to the gaz enclosure if the cell metabolism do not insure a normal pH). Delete any substrate from experimental medium. Do not add serum (which supply lipids). The Ca2+ content must be normal for contractile cells, i.e. 1.6 mM (tacking into account the absence of plasma protein); if cells do not beat, there metabolism will be too low to insure a normal delay for hypoxic response.
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