ADENOSINE STIMULATES PHOSPHATE AND GLUCOSE-TRANSPORT IN OPOSSUM KIDNEY EPITHELIAL-CELLS

We have examined the effects of adenosine on sodium-coupled phosphate and glucose transport in cultured opossum kidney (OK) cells, a continuous cell line that resembles proximal tubule. Adenosine analogues R-(-)-N6-phenylisopropyladenosine (PIA) and 2',5'-dideoxyadenosine (DDA) were employed as adenosine A1 receptor and P site-selective agonists, respectively. Sodium-dependent phosphate uptake activity (Na-P(i) symport) increased by approximately 25% above both basal and parathyroid hormone (PTH)-inhibited levels in cells treated with PIA (0.1, 1-mu-M) but not in cells treated with DDA (100-mu-M). Adenosine (PIA) also stimulated sodium-coupled 3-O-methylglucose transport by approximately 40%. Intracellular adenosine 3',5'-cyclic monophosphate (cAMP) content was inversely related to Na-P(i) symport activity in cells treated with PIA and PTH. However, changes in Na-P(i) symport activity did not consistently relate to changes in intracellular cAMP. Protein kinase C was activated 15 s after treatment of OK cells with 1-mu-M PIA. Preincubation of cells with 3-mu-M staurosporine attenuated the effect of 1-mu-M PIA on phosphate uptake. These data suggest that Na-P(i) and Na-glucose symport activities are stimulated by adenosine acting at a receptor coupled to more than one intracellular signal. It is likely that both protein kinases A and C are involved in these actions of adenosine.