Immunolocalization of A1 adenosine receptors in mammalian spermatozoa

The presence of Al adenosine receptors (A1AR) in mammalian spermatozoa was previously demonstrated by radiochemical and immunochemical detection. This study was performed to investigate the cellular location of the A1AR to de termine whether these receptors were somehow connected with ecto-adenosine deaminase and to evaluate their function in calcium uptake. By immunofluore scence staining we showed that in mammalian spermatozoa A1AR were constantl y localized in the acrosomal region. This finding was confirmed by immunogo ld detection. Confocal analyses With anti-Al and anti-ADA antibodies showed a high degree of co-localization, Calcium loading assay showed that this a ssociation was functional and affected calcium accumulation in mammalian sp ermatozoa. Therefore, we concluded that the acrosomal localization of A1AR was a constant feature in mammalian sperm. Moreover, these Al receptors wer e functionally coupled to ecto-ADA and were able to modulate calcium uptake into an IP3-gated store.