Objective To explore the effects of the clonidine-displacing substance(CDS)on the function of isolated islets from normal rats. Methods The SD rat islets were isolated by digestive method with collagenase and DNase, and incubated in RPMI 1640 culture medium overnight. Multiscreen Assay System was used to observe the effects of CDS on the function of the isolated islets. Insulin and glucagon were measured by RIA. Results Glucagon secretion of the isolated islets in incubation medium was inhibited by glucose. CDS could significantly inhibit glucagon secretion in concentration-dependent manner. Insulin secretion of the isolated islets was dependent on the glucose concentration of incubation medium. CDS could stimulate insulin secretion significantly. Nifedipine (Ca 2+ channel blocker) and diazoxide (K + channel opener) could inhibit the insulin release of the isolated islets, the effect of which could be abolished by CDS. Conclusion As an endogenous ligand of imidazoline receptors, CDS could stimulate insulin secretion, and inhibit glucagon release in the isolated islets.

Objective To explore the effects of phentolamine on the function of the islets isolated from normal rats.Methods The SD rats islets were isolated by digestive method with collagenase and DNase.Millipore Multiscreen Assay System was used to observe the effects of phentolamine on the function of isolated islets. Insulin and glucagon were measured by RIA. Results ⑴Insulin secretion of the isolated islets incubated in culture medium was glucose concentration-dependent manner. Phentolamine had stimulate insulin secretion significantly. Nifedipine (Ca 2+ channel blocker) and diazoxide (K + channel opener) had inhibit the insulin release, but their effects were abolished by phentolamine. ⑵Glucagon secretion of the isolated islets in culture medium incubated was inhibited by glucose. Phentolamine inhibited glucagon secretion significantly, and the inhibiting effect was also concentration-dependent manner,both the nifedipine and diazoxide had the effect too. Conclusion Phentolamine could stimulate insulin secretion, and inhibit glucagon secretion in the isolated islets.It maybe has some hypoglycemic effects on diabetes.