Effect of atrial natriuretic factor on cytosolic free calcium in rat glomerular mesangial cells.

Since atrial natriuretic factor (ANF) inhibits angiotensin II (ANGII)-induced mesangial cell contraction, we studied its effect on cytosolic free calcium in fura-2-loaded monolayers. ANF lowered basal calcium from 117 +/- 5 to 89 +/- 2 nM, and also reduced the ANGII-induced calcium transient. The absolute level of cytosolic calcium after ANGII was lower in cells preincubated with ANF compared to buffer. In a few cell lines, ANF had no effect on cytosolic calcium, while in all cell lines ANF had inhibited contraction. Thus, while ANF has effects on cytosolic calcium in mesangial cells, the vasorelaxant effects of ANF may require additional physiologic interactions.