Somatostatin inhibits fusion of pituitary secretion vesicles with the plasma membranes.
Somatostatin has been found to inhibit secretion vesicle fusion with the iodinated (125-I) inside-out plasma membrane vesicles (both were isolated from the anterior pituitaries). This effect of somatostatin was specific and dose-dependent (half-maximal effect at 10(-9) M). Calmodulin (10 microM), but not cyclic AMP, enhanced the fusion process between the two organelles and somatostatin inhibited calmodulin-stimulated fusion. These observations suggest that one facet of somatostatin action on hormone secretion may be its inhibition of secretion vesicle fusion with the plasma membrane.
D000818:Animals; D002147:Calmodulin / Q000494:pharmacology; D002459:Cell Fusion / Q000187:drug effects*; D002462:Cell Membrane / Q000648:ultrastructure*; D000242:Cyclic AMP / Q000494:pharmacology; D003594:Cytoplasmic Granules / Q000648:ultrastructure*; D004305:Dose-Response Relationship, Drug; D007700:Kinetics; D008297:Male; D010903:Pituitary Gland, Anterior / Q000648:ultrastructure*; D051381:Rats; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000494:pharmacology*
D002147:Calmodulin; D013004:Somatostatin; D000242:Cyclic AMP