SummarySecretion of large quantities of urokinase by cultured renal cells suggested tissue culture as a means of production to meet demand for the material and to obtain guidelines for optimization of production. Rates of secretion and overall yields of urokinase from confluent cultures of renal cells have been studied in relation to species differences, effects of passage of cells, inoculum density, and volume of maintenance media. Aided in part by an advantage gained through addition of glycine to maintenance media, it is now possible to harvest urokinase at concentrations of the order of 800 CTA units per ml. Such concentrations are of the order of 102 times that occurring in human male urine.
The change in the nuclear size of neonatal rat myocardial cells was evaluated under the culture conditions of exposure to norepinephrine (NE). Daily administration for 1 week of 0.2, 2, and 20 ng/ml NE induced a significant increase in nuclear size as a result of the dose-dependent quality of the nuclei. NE also stimulated a beating response in the cultured myocardial cells because of this dose dependency. A good correlation was found between the two markers and the NE dose dependency. Single or mononucleated myocardial cells often appeared in the NE-treated groups. Ornithine decarboxylase activity was not acutely stimulated even by 20 ng/ml NE. These observations suggest that administration of NE induces nuclear enlargement and enhances nuclear function through the stimulation of beating. Further, there may not be a direct relation between nuclear enlargement and the polyamine synthesis pathways.
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