Figure 1.

Effect of extracellular nucleotides on short-term (a) and long-term (b) activation of SK-1 in renal mesangial cells. (a) Quiescent mesangial cells were stimulated with either vehicle (2 min) or UTP (300 μM) for the indicated time periods (in minutes). (b) Cells were stimulated for the indicated time periods (in h) with either vehicle (24 h), ATP (100 μM) or UTP (100 μM). Thereafter, cell lysates containing 50 μg of protein were taken for an in vitro SK-1 activity assay as described in the Methods. Data are expressed as % of control values and are means with vertical lines showing s.d. (n=6) ^*P<0.05, ^**P<0.01, ^***P<0.001 considered statistically significant when compared to the unstimulated control value.