Abstract
Homogenates of various tissues from rats given H3-catecholamines were fractionated by centrifugation in continuous density gradients of sucrose. Endogenous norepinephrine, and exogenous (H3-labeled) norepinephrine and epinephrine were found to be localized in small particles associated with the microsomes of the heart, salivary glands and vas deferens. Radioactive norepinephrine and epinephrine were similarly distributed in the pineal gland. Administered dopamine was not associated with particles in these tissues. In the adrenal glands H3-epinephrine and H3-dopamine were found with the endogenous catecholamines in large chromaffin granules, but H3-norepinephrine was found also in the microsomal particles. Tritiated dopa, normetanephrine, and VMA were found only in the supernatant fluid from these tissues. In the brain, radioactive norepinephrine was taken up in vitro and found partly with the endogenous amine in a layer of nerve endings intermediate between the mitochondria and microsomes.
Particles from the heart containing H3-norepinephrine were enriched in tritium 20-fold relative to protein and 10-fold relative to RNA by differential and gradient centrifugation, gel filtration and treatment with sodium pyrophosphate.
Footnotes
- Received July 3, 1963.
- Accepted September 6, 1963.
- The Williams & Wilkins Company
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