POLYAMINE METABOLISM OF RAT GASTRIC-MUCOSA AFTER ORAL-ADMINISTRATION OF HYPERTONIC SODIUM-CHLORIDE SOLUTION

Oral administration of 1 mi of 3.42 M NaCl solution to rats induced sp ermidine/spermine N-1-acetyltransferase (SSAT) activity in gastric muc osa as well as ornithine decarboxylase (ODC) activity. SSAT activity i ncreased and peaked at 5 h and again at 7 h, whereas ODC activity peak ed at 6 h. SSAT mRNA also increased after 3.42 M NaCl administration t o an extent similar to the increase in SSAT activity at 5 h. Intracell ular putrescine level and DNA synthesis were increased by NaCl adminis tration. A polyamine oxidase inhibitor, N,N'-bis(2,3-butadienyl)-1,4-b utanediamine (MDL-72527), but not an ODC inhibitor, cu-difluoromethylo rnithine (DFMO), inhibited the increases in putrescine level and DNA. synthesis at 5 h. The inhibition of DNA synthesis by MDL-72527 was rev ersed by putrescine administration. In contrast, both MDL-72527 and DF MO inhibited the increase in putrescine level and DNA synthesis at 16. 5 h. These findings suggest that putrescine produced from preexistent spermidine by SSAT is responsible for the initial DNA synthesis after mucosal injury induced by NaCl and that both SSAT and ODC are involved in formation of putrescine, which is required for subsequent DNA synt hesis.