Free mitochondria and synaptosomes from single rat forebrain. A comparison between two known subfractionation techniques.

Two published subcellular subfractionation techniques employing Ficoll-sucrose or sucrose-density gradient centrifugation, respectively, are evaluated for their capacity to yield fractions containing free mitochondria and synaptosomes from a single rat forebrain. The enzymes lactate dehydrogenase, acetylcholinesterase, NAD(P)H-cytochrome c reductase, and citrate synthase, markers of different subcellular components, were used to assess the purity and integrity of the fractions. Judged by the distribution of these specific enzymatic markers, the free mitochondria obtained by the Ficoll-sucrose gradient technique were less contaminated by synaptosomes and had greater biochemical integrity than those obtained by the sucrose-gradient technique. By contrast, the synaptosomes obtained by the Ficoll-sucrose gradient technique resulted in more contamination by microsomes than those prepared in a sucrose gradient.