Relation between pancreatic islet cellular infiltration and plasma fibrinogen or alpha 1-acid glycoprotein levels in spontaneously and streptozotocin-diabetic rats: an increase in these protein levels is not necessary for inducing microcirculatory erythrocyte velocity alteration.

Abstract

Plasma levels of fibrinogen, alpha 1-acid glycoprotein (AG) and albumin, pancreatic insulitis quantitative scores, and erythrocyte velocity in the mesoappendix microvessels were measured in BB diabetic (BBD) and streptozotocin-diabetic rats (WSTZ) in order to answer the following questions: (a) Does hyperfibrinogenemia or increase in AG plasma level occur in BBD and WSTZ rats, and if so, are these alterations secondary to the hyperglycemia or to an inflammatory process such as insulitis? (b) Is there a decrease in microcirculatory flow in the BBD and WSTZ rats, and if so, is it secondary to the hyperfibrinogenemia and/or the hyperglycemia? Insulitis was present in the BBD rats after 5 weeks of disease (with a score of 2.9 +/- 0.1 vs. 1.4 +/- 0.6 in the normoglycemic controls), but absent in WSTZ rats after 5 months of disease (1.2 +/- 0.06 vs. 1.1 +/- 0.06). Increase in fibrinogen and AG plasma levels was observed in the BBD rats only and appears linked to the insulitis. The major acute phase protein AG level is increased in BBD rats already on the first day of appearance of glycosuria. In the WSTZ rats, without insulitis, chronic hyperglycemia alone did not induce an increase in fibrinogen and AG plasma levels. A decreased microcirculatory erythrocyte velocity has been found in both BBD and WSTZ rats. Thus an increase in fibrinogen or AG plasma levels is not necessary for inducing a decrease in erythrocyte velocity. Hyperglycemia is probably the main factor responsible for the decrease in microcirculatory flow in the BBD and WSTZ rats.