I. Actions of somatostatin (SS) and PACAP-related peptides on chief cells. (1). We demonstrated for the first time that chief cells possess high affinity SS receptors likely of the SSTR, subtype by binding studies. Receptor occupation was regulated by agents that activate PKC or adenylate cyclase. SS receptor activation decreased activation of adenylate cyclase but had no effect on pepsinogen release by various secretagogues. (2). 125I-PACAP bound with high affinity to receptors on chief cells. Binding studies showed 125I-PACAP bound with high affinity to VIP receptors and low affinity to secretin receptors. Forty percent of the maximal ability of PACAP to stimulate pepsinogen release was due to occupation of VIP receptors and 60% to secretin receptors. II. Role of calcium in secretagogue-stimulated secretion from pancreatic acini. Using thapsgargin (TG), BHQ and cyclopiazonic acid (CPA) sustained enzyme secretion by secretagogues that increase IP3 (1,4,5) was shown not due to an increase [Ca2+]i per se, however, potentiation was. III. Cellular basis of action at NMB receptors. Using C-6 glioblastoma cells and NMB-receptors transfected into Balb 3T3 cells, NMB-R activation was shown to activate PLC, increase [Ca2+]i and IP3 and not to activate adenylate cyclase. The transfected receptor and native NMB-R functioned identically in regard to kinetics of binding, stoichiometry, internalization, coupling to G proteins and activation of PLC suggesting these cells will be useful to explore ligand receptor interactions and molecular biological studies of receptor structure function. IV. Role of CCK receptors in experimental pancreatic cancer tumorigenesis. In collaboration with R.H. Bell, Dept. of Surgery, U. of Cincinnati, School of Medicine, overexpression of high affinity CCK receptors in premalignant and malignant tumors was shown and it was proposed this may result in a growth advantage for these tumors.
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