Differences in basic proline-rich proteins in rat parotid saliva following chronic isoproterenol treatment or maintenance on a liquid diet.

The basic proline-rich proteins (BPRP) in the stimulated parotid saliva of rats treated for 8 days with isoproterenol and rats fed a liquid diet for 2 weeks were compared to those in the stimulated parotid saliva of untreated rats fed a stock pelleted-diet (control). In the control, the BPRP were separated into 5 groups designated Peak A (the basic proline-rich glycoprotein), SP-1, SP-2, SP-3 and SP-4. The percentage of BPRP in each group was as follows: Peak A, 6.5 per cent; SP-1, 37 per cent; SP-2, 6.5 per cent; SP-3, 32.4 per cent; SP-4, 17.6 per cent. In the parotid saliva of rats fed the liquid diet, proteins corresponding to Peak A and SP-2 were not present, the proportion of BPRP in SP-4 was increased to almost 90 per cent while the proportions of material in SP-1 and SP-3 were reduced to 3 and 8 per cent, respectively. In the saliva of rats subjected to chronic isoproterenol treatment, a protein corresponding to SP-4 was not present; proteins corresponding to Peak A, SP-1 and SP-3 were present and in amounts similar to their proportion in untreated rats although material in SP-2 increased to 36 per cent.