The order of islet microsvascular cellular perfusion is B → A → D in the perfused rat pancreas

Abstract

In order to determine whether microsvascular blood flow is important in the regulation of intra-islet cellular interactions, rat pancreata were isolated and perfused in vitro, both anterogradely or retrogradely, with and without anti-insulin or anti-somatostatin γ-globulin. Expressed as percent change, anterograde infusion of insulin antibody increased efflux concentrations of glucagon (110 ± 20%, P < 0.0005) and somatostatin (2,112 ± 73%, P < 0.0005) above their respective control. Retrograde infusion of insulin antibody did not affect efflux concentrations of glucagon (P < 0.50) or somatostatin (P < 0.50). The anterograde infusion of anti-somatostatin antibody had no effect upon insulin (P < 0.50) or glucagon (P < 0.50) efflux concentrations, whereas retrograde anti-somatostatin antibody infusion produced immediate increases in efflux concentrations of both insulin (115 ± 33%, P < 0.0005) and glucagon (77 ± 8%, P < 0.0005). These results strongly suggest that (a) the vascular compartment is important in the regulation of intra-islet cellular interactions and further suggest that (b) the order of islet cellular perfusion and interaction is from the B cell core outward to the mantle, and (c) the mantle is further subordered with the majority of D cells downstream or distal to the majority of A cells. Thus, in the vascular compartment, B cells inhibit A-cell secretion and A cells stimulate D-cell secretion.