Post-translational processing of atrial natriuretic factor. A study using a novel cell culture system.

Abstract

In the present work, a reproducible cell culture system using adult rat atrial cardiocytes was developed to study ANF processing. Freshly isolated atrial cardiocytes stored high molecular weight ANF (38.0 $\pm$ 4.5 pg/$\mu$g of DNA) and released almost exclusively (83.3% $\pm$ 6.7%) low molecular weight ANF, at an average rate of 12 pg/hour/$\mu$g of DNA. The cell content and the rate of release of ANF decreased over 15 days in culture to 3.9 $\pm$ 1.2 pg/$\mu$g of DNA and 0.32 pg/h/$\mu$g of DNA $\pm$ 0.08 respectively and 62.7% $\pm$ 6.3% of the released peptide was of a low molecular weight. Cultures of non-cardiocytes, superfused with exogenous proANF, did not process the peptide. There was no correlation between the changes in cell population and the reduction in processing. Therefore, atrial non-cardiocytes are not involved in ANF processing. The results presented in this work vary from other reports which found that ANF processing in cultures is absent. The discrepancies may be due to differences related to serum-free culture conditions versus serum supplemented cultures. This suggests that factors present in the serum may be responsible for maintaining ANF processing activity in culture. (Abstract shortened by UMI.)