Microsphere distribution in the pancreas of anesthetized rats. Alloxan stimulates the blood flow to all islets whereas glucose only affects the blood perfusion of a subgroup of islets.

CONCLUSION: Islet blood flow stimulation induced by alloxan leads to an increased blood perfusion in all islets, whereas glucose induces a flow increase only in a subgroup of islets.
BACKGROUND: The aim of the present study was to investigate if an increased islet blood flow was associated with an enhanced total number of perfused islets, or whether only a subgroup of the islets increased their blood flow.
METHODS: For this purpose, the whole pancreatic and islet blood flow was measured with a microsphere technique (4.5 x 10(5) microspheres/kg body wt) in anesthetized Sprague-Dawley rats. Blood flow measurements were made 3 min after an i.v. injection of 1 mL of saline, alloxan (75 mg/kg body wt), or D-glucose (300 mg/mL).
RESULTS: Alloxan reduced whole pancreatic blood flow by 50%, but almost doubled islet blood flow. Glucose did not affect whole pancreatic blood flow, but increased islet blood flow 100%. Approximately 10% of the islets in control and glucose-injected rats contained microspheres, compared with about 25% in alloxan-injected rats (P < 0.001). When the islets containing a certain number of microspheres were compared, alloxan induced a homogeneous shift of the curve to the right, i.e., increased the number of islets that contained all amounts of microspheres. Glucose preferentially increased only the fraction of islets containing > or = 3 microspheres.