Lipopolysaccharide-Induced Changes in Vascular Reactivity of Diabetic Rat Aorta

Seo, Ye Kyung; Chung, Sang Won; Nam, Jik Hwa; Sin, Byoung Ho; Kim, Dong Hee; Kim, Jung Guk; Ha, Sung Woo; Kim, Bo Wan

Abstract

Backgound: Hemodynamic deteriorations in diabetes mellitus may be mediated by increased contractile response to catecholamines and/or by decreased relaxative response to vasodilators such as acetylcholine(Ach). Decrease in peripheral vascular reactivity to vasoconstrictor was known to be an ominous sign that happens during sepsis or after injection of bacterial lipopolysaccharides(LPS). In this study, we compared the effects of LPS on function of diabetic rat aorta with impaired vascular reactivity with those of control rat aorta.
METHODS
Contractile responses to cumulative concentrations(10'M to 3X10'M) of norepinephrine (NE) were measured in aorta isolated ftom the control and 4 to 5-week streptozotocin-induced diabetic rat at 6 hours after LPS treatment to compare with contractile responses of untreated group. We measured relaxative responses to cumulative concentrations(10'M to 10M) of Ach and nitroprusside (NTP) in these aortas contracted submaximally by NE.
RESULTS
Diabetic rat aortas showed significantly more impairment in relaxative responses to Ach than control rat aortas before LPS treatment(p0.05 = 0.0l). LPS treatment in those diabetic rat aortas decreased contractile responses to NE by 26.6%(p < 0.01); the changes were sirnilar to those of control (30.9%, p0.01). Relaxative responses to Ach were also significantly decreased by 25.0%(p 0.01) after L.PS treatment; the changes were similar to those of control(34.1%, p0.01). However relaxative responses to NTP were not changed in control and d.iabetic rat aortas by LPS treatment.
CONCLUSION
These results suggest that diabetes may induce impairment in endothelium-dependent vascular relaxation and there rnay be no difference of L,P,S-induced effects on hemodynamic deterioration between 4 to 5-week diabetic and control rats.