Renin secretion from rat renal cortical cell suspensions

Renin secretion of rat renal cortical cell suspensions was studied as a functionof variations in the composition of the suspension media. Renin secretion was determined by incubating samples of the suspension media with rat renin substrate and measuringthe angiotensin I generated by radioimmunoassay. Increasing the medium sodium concentration (50-144 meq/liter) linearly decreased the rate of renin secretion. This relationship was unaffected by adding ouabain (10 minus 3 M) to the suspensions. The addition of furosemide (from 10 minus 5 to 10 minus 3 M) stimulated renin secretion. Considered with previous observations, these results suggest that renin secretionis controlled by some function of sodium on the lumenal boder of the macula densa cells.