Despite the high rate of occurrence of both diabetes and
hypertension in humans, the cardiovascular effects of the two conditions have not been investigated when they occur simultaneously. Thus this study examined the vascular effects of simultaneous
type 2 diabetes and
renal hypertension on endothelial function. Serum
malondialdehyde and systolic blood pressure (SBP) were measured,
glucose tolerance test (GTT) was performed, and concentration-response to
phenylephrine (PE) in the absence and presence of nitro-
l-arginine methyl ester (
l-NAME),
acetylcholine and
sodium nitroprusside were conducted on aortic rings from diabetic control,
type 2 diabetes,
sham-operated, renal hypertensive, and simultaneous
type 2 diabetes plus
hypertension rats respectively.
Hypertension, diabetes, and simultaneous diabetes and
hypertension were associated with either increased or decreased maximal responses (E(max)) of PE dependent on in the presence or absence of
l-NAME. There was also increased serum
malondialdehyde and decreased E(max) of
acetylcholine. Thus simultaneous
hypertension and diabetes caused a greater decrease in E(max) of
acetylcholine compared to that seen with either diabetes or
hypertension alone higher than that seen in
hypertension. The
blood glucose during GTT was lower than that seen in diabetes groups. Thus simultaneous
type 2 diabetes and the SBP was
renal hypertension is associated with improved
glucose tolerance, but with further deterioration of endothelial dysfunction compared with either condition alone.