Comparison of adenosine uptake and endogenous adenosine-containing cells in mammalian retina.

Autoradiographic techniques were used to label [3H]-adenosine and [3H]-cyclohexyladenosine accumulating cells in rabbit, mouse, and ground squirrel retinas. Immunohistochemical methods revealed the distribution of cells that stained for endogenous adenosine. Comparisons of these two markers revealed for all three species that the distribution of specific subpopulations of retinal cells that store or accumulate the purine nucleoside, adenosine, is similar. For all three species, cells localized in the ganglion cell layer accumulated adenosine and exhibited adenosine-like immunoreactivity (ALIR). A smaller proportion of cells localized in the inner nuclear layer were labeled for ALIR, while a larger proportion of cells in this layer accumulated adenosine. Subtle differences between species are presented. However, the general similarities of the distribution of these two putative purinergic markers supports the evidence that a discrete adenosinergic neurotransmitter/modulatory system is present in the retina.