4. Discussion. This study showed that IV bolus injection of sulfated gastrin- 34 increased the levels of ghrelin in plasma in a dose-dependent manner in cattle. The results were, in general, in agreement with those obtained earlier in fasted rats I10.20]. However, gastric microdialysis and abdominal studies that human had effect on the of in 178l Lippi et al. 117lshowed that gastrin-17 inhibited isolated rat vagally prestimulated ghrelin release in the between earlier Some factors may account for the discrepancy that results and the present data. On important factor ferent forms of gastrin tide were administered. In the present study, bovine sulfated gastrin-34 and -17 were effective in the stimulation of ghrelin in cattle. However, human Leu15-gastrin- 17, which has a different N-terminal amino acid sequence from rat gastrin, showed no effect on ghrelin secretion in rats. Other factors such as of administration, doses of peptide, and feed routes ing conditions, may have influenced the results. The duration of increment of ghrelin was long in the high dose of gastrin injected group (Fig. 3A and B). We suggest that the long duration of ghrelin release may be related to the long duration of plasma high gas- trin levels after the injection of gastrin-34. In the present study, elevations of plasma total gastrin levels lasted 45, 60 and 150 min after the administration of0.8.4.0and20.0 jug/kg BW of gastrin-34, respectively. Walsh et al. 139] reported a half life for non-sulfated gastrin-34 after rapid intravenous injection that was 8-fold longer than that for non-sulfated gastrin-17. Hirst et al. [14] showed that the metabolic clearance rate of non-sulfated gastrin-6 was 3- and 6-fold higher than that of human non-sulfated gastrin-17 and sul- fated gastrin-6. respectively. These reports imply that increasing N-terminal extensions of gastrin or sulfation of tyrosine residues