Effects of diabetes and insulin resistance in pregnant rats on ex vivo vascular reaction to magnesium.
The purpose of this study was to investigate the effects of diabetes and insulin resistance during pregnancy on the ex vivo vascular reaction to magnesium. Female Sprague-Dawley rats were made diabetic by intravenous injection of alloxan, or insulin resistant by fructose feeding. The rats were allowed to mate and sacrificed on Day 19 of pregnancy. Aortic rings were isolated and mounted in organ baths for measurement of isometric tension. The rings were contracted with 10(-7) M phenylephrine and cumulative concentration-response curves for magnesium (1-12 mM) were determined in the presence and absence of 10(-4) M Nomega-nitro-L-arginine methyl ester (L-NAME) or 10(-5) M indomethacin. The relaxation response to magnesium was significantly decreased in pregnant rats compared with non-pregnant rats. Pregnant rats with diabetes or insulin resistance had greater impairment in the relaxation responses to magnesium compared with normal pregnant rats. The effects of diabetes and insulin resistance on magnesium-induced relaxation in pregnant rats were not altered in the presence of L-NAME and indomethacin. The results suggest that diabetes and insulin resistance aggravate the alteration in magnesium-induced vascular relaxation observed in pregnancy, and this may be due in part to impairment to mechanisms other than the nitric oxide-cyclic guanosine monophosphate and cyclooxygenase pathways.
Ettarh
R R
RR
Department of Physiology, College of Medicine, University of Lagos, Idi-Araba, Lagos, Nigeria. ettarh@yahoo.com
Arikawe
A P
AP
D000496:Alloxan; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology*; D001786:Blood Glucose / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism* / Q000503:physiopathology; D005260:Female; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D007333:Insulin Resistance / Q000502:physiology*; D008274:Magnesium / Q000378:metabolism* / Q000494:pharmacology; D009126:Muscle Relaxation / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D011247:Pregnancy; D011254:Pregnancy in Diabetics / Q000378:metabolism* / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley
D001786:Blood Glucose; D000496:Alloxan; D008274:Magnesium; D019331:NG-Nitroarginine Methyl Ester; D007213:Indomethacin