Responses of juxtaglomerular cell suspensions to various stimuli

Cell suspensions were prepared from rat renal cortical tissue by dispersion with 0.1% collagenase. Unit gravity sedimentation in a 1%-4% Ficoll gradient resulted in a single-cell suspension enriched in juxtaglomerular (JG) cells. Both the cellular renin activity and the amount of renin released into the supernatant increased with time when the suspensions were incubated for 1 hour at 37 degrees C in tissue culture medium. These cells responded to epinephrine and norepinephrine by increasing both synthesis and release of renin. The response was blocked by timolol but not by phenoxybenzamine. Cell suspensions prepared in the same manner but using 0.25% trypsin as the dispersing enzyme neither synthesized nor released renin into the tissue culture medium when similarly incubated. Trypsin-dispersed cells did not respond to catecholamine stimulation. Renin synthesis and release in collagenase-dispersed JG cells were unaltered by changes in Na, K, or Ca ion concentrations. Angiotensin II inhibited release, while saline extracts of clipped kidney from renal hypertensive rats stimulated renin release by these cells.