Effects of Norepinephrine on Neonatal Rat Cardiocyte Growth and Differentiation

• Published in: In Vitro Cellular & Developmental Biology Vol. 26; no. 3; pp. 229 - 236
• Main Authors: Thomas A. Marino, Ruth Anne Walter, Elizabeth Cobb, Maria Palasiuk, Parsons, Thomas, Mercer, W. Edward
• Format: Journal Article
• Language: English
• Published: Largo, MD Tissue Culture Association, Inc 01-03-1990; Society for In Vitro Biology
• Subjects: Animals; Animals, Newborn; Biological and medical sciences; Catecholamines; Cell cycle; Cell cycle, cell proliferation; Cell Differentiation - drug effects; Cell growth; Cell nucleus; Cell Nucleus - drug effects; Cell physiology; Cells, Cultured; Culture Media; Cultured cells; DNA; Endothelial cells; Fundamental and applied biological sciences. Psychology; Heart - drug effects; Hepatocytes; Isoproterenol - pharmacology; Mitosis - drug effects; Molecular and cellular biology; myocardium; Myocardium - cytology; myocytes; Myofibrils; Myofibrils - drug effects; Myofibrils - ultrastructure; Norepinephrine; Norepinephrine - pharmacology; Nuclear Proteins - analysis; Proliferating Cell Nuclear Antigen; Propranolol - pharmacology; Rats; Cell proliferation; Cell culture; Rat; Rodentia; Cell division; DNA synthesis; Cell differentiation; Vertebrata; Mammalia; Newborn animal; Animal; Binucleate cell; Immunofluorescence; Heart cell
• DOI: 10.1007/BF02624452
• EISSN: 2327-431X; 1475-2689
• ISSN: 0883-8364

Norepinephrine stimulates the growth in size of nondividing neonatal cardiocytes. During this time the neonatal cardiocyte is in a period of transition in which the cell can synthesize DNA and yet does not divide. Because the cell undergoes karyokinesis without cytokinesis the objective of this study was to determine whether the norepinephrine-induced growth in size of the neonatal cardiocyte was accompanied by an increase in a) the number of cardiocytes synthesizing DNA, b) the number of binucleate cardiocytes, and c) organized myofibrils. One- to four-d-old neonatal rat heart cells were isolated and placed in serum-free medium which was then supplemented with serum, norepinephrine, norepinephrine plus propranolol, or isoproterenol. After 4 d the number and size of the cells was determined using a Coulter counter. In other cultures cardiocytes were fixed on Days 0, 1, 2, and 4, and an increase in the number of binucleate cardiocytes was found in all treatment groups including controls. However, the rate of binucleation was faster in the norepinephrine group. It was also determined by proliferating cell nuclear antigen (PCNA) antibody staining that by Day 4, over 50% of the cardiocytes were in the cell cycle. The percentage of cells in which PCNA could be detected was higher in the norepinephrine and norepinephrine plus propranolol groups. Furthermore, there was a concomitant increase in the amount and organization of myofibrils in the catecholamine-treated cardiocytes.