Effects of K+Channels Inhibitors on the Cholinergic Relaxation of the Isolated Aorta of Adult Offspring Rats Exposed to Maternal Diabetes

Abstract

Vascular disease has importance in chronic diabetes mellitus but long-term impact of maternal diabetes (MD) on vascular function in the offspring is poorly investigated. This study aimed to examine the alterations produced by MD in K⁺ channels activity on endothelium-dependent aortic relaxation induced by acetylcholine (ACh) in adult offspring rats. Diabetes mellitus was induced in female Wistar rats by streptozotocin (STZ; 42 mg/kg, i. p.) injected on the 7^th day of pregnancy. Body weights of offspring rats from diabetic mothers (O-DR) were significantly lesser than those of offspring rats from control mothers (O-CR). At 120 days of age, triglyceride but not glucose and cholesterol level was significantly higher in O-DR than in O-CR. In aortic preparations from O-DR, norepinephrine (NE)-induced contractions were significantly higher than those observed in O-CR. In aortic preparations from O-DR precontracted with NE (1 μM), vasorelaxant response to either ACh (0.1, 1 and 10 μM) or sodium nitroprusside (0.1, 1 and 10 nM) was significantly reduced when compared to O-CR. In both groups, vasorelaxant responses to ACh were reduced in the presence of tetraethylamonium chloride and 4-aminopyridine. However, pretreatment with glybenclamide reduced vasorelaxant effects of lowest concentration (0.1 μM) of ACh only in preparations from O-CR. Our results suggest a reduced K⁺ _ATP activity in the cholinergic relaxation of aortic rings of adult offspring born to STZ-diabetic mothers.

Key words

acetylcholine - aorta relaxation - K⁺ _ATP channels - maternal diabetes - offspring

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