Two distinct receptors for ATP can be distinguished in Swiss 3T6 mouse fibroblasts by their desensitization.

The stimulation of calcium efflux from Swiss 3T6 mouse fibroblasts by extracellular ATP was studied. It was found that the cells could be desensitized to ATP by a previous exposure to the nucleotide, lending support to the theory that this is a receptor mediated process. Another ATP-receptor mediated process in Swiss 3T6 cells, that is also subject to desensitization, causes the permeabilization of the plasma membrane to nucleotides and other normally impermeant compounds [Gonzalez et al., J. Cell. Physiol. 139:109 (1989)]. Here we demonstrate that selective desensitization of the ATP-dependent calcium mobilization pathway can be achieved without affecting ATP-induced permeabilization. Data are presented in support of the existence of multiple ATP-receptors (purinoceptors) in Swiss 3T6 cells.