Effect of the somatostatin analogue SMS 201-995 on ATP-dependent calcium transport of basolateral vesicles from human duodenum.

Brush border membrane vesicles (BBMV) and basolateral membrane vesicles (BLMV) were simultaneously prepared from surgically resected pieces of morphologically intact human duodenum with a modified Percoll gradient centrifugation method. Alkaline phosphatase was enriched 20-fold in BBMV, whereas (Na+ + K+)-stimulated adenosine triphosphatase was enriched 15-fold in BLMV. BBMV and BLMV were preincubated with 3 pM synthetic somatostatin-14 or 3 μM SMS 201–995 for 10min at 5°C. In BBMV calcium, sodium, d-glucose, L-alanine, and D-mannitol uptake was unaffected by somatostatin-14 and SMS 201–995. In BLMV wc found two Ca++ transport systems: Na+/Ca++ exchange and ATP-driven Ca++ transport. Somatostatin-14 had no effect on either of the two transport mechanisms. SMS 201–995 had no effect on Na+/Ca++ exchange but significantly inhibited basolateral ATP-dependent Ca++ transport (−40% ± 5%. p < 0.005).