I analyzed for free and sulfate-conjugated catecholamines and DOPA (3,4-dihydroxyphenylalanine) in four aliquots of a single plasma pool with use of Upjohn's "Cat-A-Kit" (catecholamines radioenzymatic assay kit [3H]. One aliquot was a clear plasma control; the others were supplemented with different concentrations of lysed human erythrocytes, to investigate possible interference by hemolysis with analysis for norepinephrine, epinephrine, dopamine, or DOPA in plasma. I observed no statistically significant difference that could be attributed to the degree of hemolysis between control and treatment groups for DOPA or any catecholamine fraction. Hemolysis in plasma from improper collection or processing techniques apparently does not preclude accurate and precise quantitation of free or sulfate-conjugated catecholamines or DOPA with the Cat-A-Kit.
The cocaine‐ and amphetamine‐regulated transcript (CART) was first isolated from rat striatum following the acute administration of cocaine or amphetamine. It was quickly determined that CART or CART peptide was expressed in a variety of tissues affecting a wide range of important processes. The function of these areas have grown to include feeding behavior, pleasure and reward, diabetes, ovarian follicle development, bone remodeling and anxiety. In spite of the relevance of these conditions as therapeutic targets, development of small molecules to modulate these systems has been impeded by the lack of an identified receptor for CART peptide. Localization studies suggest that CART and CART peptide are located in similar areas: hypothalamus, pituitary and adrenal gland. Cells isolated from these tissues have provided information delineating much of the current state of knowledge regarding the CART peptide receptor. We have characterized the signaling pathways activated by CART peptide in the Rat 2 fibroblast cell line. We observed a pertussis‐toxin sensitive inhibition of cAMP production, and increased phosphorylation of extracellular signal regulated kinase 1 and 2. These results suggest that the CART peptide receptor is more widely expressed than previously appreciated. These CART peptide studies in Rat 2 cells provide important information that will aid in the identification of CART peptide receptor.
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