Extraction of corticosterone from cell homogenates and subcellular fractions of the rat adrenal cortex. III. ACTH-induced temporal subcellular redistributions of steroid precursors to corticosterone

Cholesterol, pregnenolone, progesterone, 11-deoxycorticosterone (11-DOC) and corticosterone were quantitated in subcellular fractions isolated from in vivo adrenocorticotropin (ACTH)-stimulated rat adrenal zona fasciculata/reticularis. Six adrenal subcellular fractions separated by discontinuous sucrose gradient centrifugation (lipid, 0.125 M sucrose, cytosolic, microsomal, mitochondrial and nuclear) were extracted with alkaline ether/ethanol and assayed by high pressure liquid chromatography (HPLC). Lipid fractions contained the major cholesterol stores, while most pregnenolone and progesterone was found in lipid, microsomal and mitochondrial fractions. The 0.125 M sucrose and cytosol fractions together contained approximately 75% of the total 11-DOC and corticosterone. The five steroids were only present in small amounts in organelle fractions containing steroidogenic enzymes. Homogenate and lipid fraction cholesterol decreased between 10 and 15 min and again 30 min after ACTH injection. In the homogenate, lipid, microsomal and mitochondrial fractions, pregnenolone and progesterone were increased after ACTH injection; peak pregnenolone and progesterone concentrations were often measured in adrenal gland sucrose, cytosolic, microsomal and mitochondrial fractions 15 to 20 min after rats were injected with ACTH. Although ACTH increased 11-DOC and corticosterone in all but the mitochondrial and nuclear fractions, the sucrose, cytosolic and microsomal 11-DOC, and cytosolic corticosterone increased most dramatically. In many fractions, peak 11-DOC and corticosterone concentrations were most often observed between the 10 and 15 min periods and again at 30 min.

Anionic forms of brain arylsulfatase B: evidence for a phosphorylated form in man and monkey

Arylsulfatase A, B and an anionic form of B were separated by DEAE-cellulose column chromatography from the brains of man, monkey, rabbit, rat and chicken. The relative proportion of brain arylsulfatases differed from one species to the other. The anionic form of arylsulfatase B was a minor component as compared to arylsulfatase A or B in human and monkey brains while it was a major component in rat and chicken brains. Anionic arylsulfatase B was found in fetal human brains and in newborn monkey brain. In the rat brain, the activities of arylsulfatases A and anionic B showed an increasing trend during development, reaching a peak around 20 days after birth, without any change in their proportions. Treatment with Escherichia coli alkaline phosphatase resulted in the conversion of a major portion (about 70%) of the anionic arylsulfatase B of human and monkey brains into a less charged form which remained unbound to DEAE-cellulose. This conversion by phosphatase was inhibited by inorganic phosphate. Rat and chicken brain anionic arylsulfatase B was not susceptible to alkaline phosphatase. Vibrio cholerae neuraminidase treatment did not significantly affect the charge on anionic arylsulfatase B from any of the species. The results suggested a phosphorylated form of anionic arylsulfatase B exclusively in the primate brain.

Arylsulphatase C and estrone sulphatase of sheep hypothalamus, preoptic area, and midbrain: separation by hydrophobic interaction chromatography and evidence for differences in their lipid environment

Arylsulphatase C and estrone sulphatase activities of sheep hypothalamus-preoptic area-midbrain were examined for their susceptibility to phospholipase action. Russel's viper phospholipase A could completely inactivate estrone sulphatase without affecting arylsulphatase C. The latter was partially inactivated by S. aureus phospholipase C but not by C. welchi phospholipase C. Both arylsulphatase C and estrone sulphatase were inactivated to different extents by sodium deoxycholate, which is known to activate the intrinsic phospholipases of brain. Hydrophobic interaction chromatography on phenyl-Sepharose resulted in the differential elution of arylsulphatase C and estrone sulphatase. The results suggest that one enzyme is not responsible for arylsulphatase C and estrone sulphatase activities.

Flow rate determination using computed tomography

A method of measuring flow in a large vessel by using a CT scanner is described. It has been shown that this is a simple, accurate and reproducible method in an experimental model. Possible clinical applications and limitations of this method of measuring flow are briefly considered.