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Effect of BRPP on neonatal rat cardiomyocyte culture during in vitro norepinephrine and isoprotenerol stimulation

Introduction. Myocardial sympathetic activity is increased in heart failure, and norepinephrine (NE) stimulate apoptosis of cardiomyocytes through α - and β -adrenergic pathway. Isoprotenerol (ISO), as well as NE, induces apoptosis in neonatal rat cardiomyocyte cell (NRC) culture. BRPP (brain-pig polypeptide) has shown positive effect on growth in several cell-lines (CHO-K1, BHK) as well as some primary cell cultures. Our goal was to test influence of BRPP on NRC culture during β -adrenergic pathway stimulation. Material and Methods. Primary ventricular cardiac myocytes were prepared from 6-8 days old Fisher rats hearts were removed, ventricles pooled and ventricular cells isolated with Worthington Neonatal Cardiomyocytes Isolation Kit. Isolated cells were plated to 24-well culture plates (Falcon) at density of 1, 25x105 cells/cm2 in DMEM with 10% FBS. NRC were maintained at 37oC in humidified air with 5% CO2. After 24 hours, cells were treated with NE (1 or 10 mcmol/L), ISO (1 or 10 mcmol/L) and with or without BRPP 0, 1 mcgr/cm2, as well as with NE (1 or 10 mcmol/L) + BRPP and ISO (1 or 10 mcmol/L) + BRPP. 48 hours after treatment cells were harvested and counted. BRPP is isolated from fresh young pig brain tissue by own procedure. Results. NRC treated with BRPP has shown significantly (p=0, 002) higher cell number vs. control. Addition of BRPP to any other selected NRC group have shown significant increase vs. without BRPP as follows: with NE 1 mcmol (p=0, 001), NE 10 mcmol (p=0, 003), ISO 1 mcmol (p=0, 002) and ISO 10 mcmol (p=0, 002). NRC groups + NE 1 mcmol treatment with BRPP had significantly higher cell numbers vs. sample without BRPP (p=0, 001) while with NE 10 mcmol significant difference was not observed. NRC groups with ISO and BRPP have shown significant increase vs. without BRPP for ISO 1 mcmol and ISO 10 mcmol. Conclusion. BRPP has shown its potential stimulation NRC in vitro alone or with different proapoptotic agents and in different amounts. Its relevance in neonatal cardiac pathology remains to be elucidated. Acknowledgments. Research supported by 0058001, 0058010 Grants MZOŠ-Croatia and PLIVA Inc.

cardiomyocyte cell; neonatal rat; brain-pig polypeptide

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