Hyperglycemia-induced small intestinal dysrhythmias attributed to sympathovagal imbalance in normal and diabetic rats.

Abstract

Hyperglycemia is known to induce dysrhythmias in the stomach; however, it is unknown whether they are also induced in the small intestine. Autonomic dysfunction is commonly noted in diabetes but the role it plays in hyperglycemia-induced dysrhythmias remains unknown. This study aimed to explore the effects of hyperglycemia on intestinal myoelectrical activity and the role of autonomic functions in hyperglycemia. Small intestinal myoelectrical activity (slow wave and spike activity) and autonomic functions (assessed by the spectral analysis of heart rate variability) were measured in Goto-Kakizaki diabetic rats and control rats treated with acute glucagon. Blood glucose was measured and its correlation with intestinal slow waves was determined. (1) The diabetic rats showed reduced regularity in intestinal slow waves in fasting and fed states (p < 0.001 for both), and increased sympathovagal balance (p < 0.05) in comparison with the control rats. The regularity in intestinal slow waves was negatively correlated with the HbA1c level in all rats (r = -0.663, p = 0.000). (2) Glucagon injection in the control rats induced transient hyperglycemia, intestinal slow wave dysrhythmias and impaired autonomic functions, similar to those observed in the diabetic rats. The increase in blood glucose was correlated with the decrease in the regularity of intestinal slow waves (r = -0.739, p = 0.015). Both spontaneous and glucagon-induced hyperglycemia results in slow wave dysrhythmias in the small intestine. Impairment in autonomic functions (increased sympathovagal balance) may play a role in hyperglycemia-induced dysrhythmias.