By Jesús Aguado MADRID (Reuters) -The European Central Bank has asked some lenders to detail their exposure to Spain’s Grifols and its related entities, after the drugmaker was last week accused of manipulating its financial accounts by a short-seller, sources said. Grifols denies the accusations by Gotham City Research that it has manipulated its debt and earnings through transactions with a related entity, to the effect that its leverage ratio is nearly double what Grifols has reported. The ECB has in recent days contacted a number of banks to get them to outline their current exposure to Gr…