Effect of elevated glucose on contractile and relaxant response of aortic strips in Indian bonnet monkey (Macaca radiata radiata).

Vascular contractile response to phenylephrine and potassium chloride were examined in strips of isolated thoracic aorta from non-diabetic monkeys with and without intact endothelium exposed to glucose (5.5 mM; control) and (11 mM; high) concentration. Acetylcholine causes relaxation in isolated aortic strips with intact endothelial cells while it causes contraction in aortic strips with damaged endothelial cells. In preparations with intact and damaged endothelium, there was a significant increase in the maximal contractile response to potassium chloride when added cumulatively, on exposure to elevated glucose (11 mM) concentration as compared to control. It was also observed that relaxant response to acetylcholine and sodium nitroprusside in control (5.5 mM) and high glucose (44 mM) concentration. Endothelium-dependent relaxation to acetylcholine decreased significantly in the presence of 44 mM glucose. In preparation without endothelium, contraction caused by acetylcholine increased in the presence of glucose (44 mM). Direct smooth muscle relaxation to sodium nitroprusside remained unchanged in aortic strips with and without endothelium. Relaxation response to sodium nitroprusside decreased in strips with damaged endothelium on exposure to high glucose when compared to control glucose.

Intravenous glucose tolerance test in Macaca radiata radiata.

A reliable method for performing sensitive intravenous glucose tolerance tests in monkeys has been standardized. This helps in assessment of beta cell function. A normal curve for glucose disposal is constructed. A high variability in insulin levels is also documented.