title: Further studies on properties of renin granules isolated from rat kidney cortex.
abstract: The properties of renin granules isolated from rat renal cortex were studied. Renin granules were thermolabile since in 10 min at 0 degrees C twice as much renin was released as at +37 degrees C. Addition of Ca++ (10(-6) M - 10(-2) M) did not affect the spontaneous release at +37 degrees C, pH 6.5, during 10 or 30 min incubation. However, when pH was elevated to above 7, renin release was significantly increased by Ca++ (10(-3) M). Additions of various amounts of KCl, NaCl or MgCl2, which increased the osmolality less than 20 mOsm/kg, did not affect the stability of the renin granules. Mg-ATP (0.5 and 5 mM) as well as Mg-GTP (5 mM) stabilized renin granules at +37 degrees C, pH 6.5, but the corresponding nitrogen analogues Mg-AMP-PNP and Mg-GMP-PNP (0.5 and 5 mM) were not effective. Neither did Mg-AMP (5 mM) nor ATP (5 mM) without Mg++ affect the renin release. No stabilization was observed by Mg-ATP and Mg-GTP in the purified granule preparations. The results suggest the importance of the cleavage of the terminal phosphate in the stabilization process. When the granules prepared at 300 mOsm/kg were first kept at hyperosmotic medium (range 300-1650 mOsm/kg) and then moved back to 300 mOsm/kg, the granules tend to lyse the more the greater was the reduction of the osmolality. The granules were more stable in isotonic sucrose than in isotonic ionic medium.
mesh_terms: D002122:Calcium Chloride / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D003594:Cytoplasmic Granules / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007672:Kidney Cortex / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D009711:Nucleotides / Q000494:pharmacology; D009994:Osmolar Concentration; D012083:Renin / Q000378:metabolism*; D013696:Temperature
chemical_list: D002712:Chlorides; D009711:Nucleotides; D012083:Renin; D008274:Magnesium; D002122:Calcium Chloride