Playstation Network Pre-Paid Card Function Doubt, HELP wanted

Hi, I have a doubt about PSN cards. Let's say I have a card from a specific country (let's say Spain) can I use it to buy something from another country's PSN store, so long as the countries both use the same currency? (For example, Ireland, both Spain and Ireland use the Euro as their currency). Any help concerning this problem would be appreciated, thank you in advance =D