抄録
Time sequential impairement in endothelium-dependent and-independent vasodilation of subendocardial arterioles (Endo-A) were evaluated in hypertensive (HT) canine hearts (2-clip and 2-kidney model). Then, changes in asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) and dimethylarginine dimethylaminohydrolase (DDAH), which degrades ADMA were studied in spontaneously hypertensive rats (SHR) and diabetes mellitus rats (DM) in early stage. In an early stage of HT (4week), the endothelium-dependent response of Endo-A was impaired, and in the later stage (12week), both the endothelium-dependent and independent responses of Endo-A were impaired. These sequential changes may be related with the degree of decreased coronary flow reserve in progression of LVH. ADMA was elevated and DDAH activity was decreased significantly in SHR, but not DM. This may indicate that hypertension increased ADMA by reducing DDAH activity, whereas increased DDAH in early stage of DM may compensate for endothelial dysfunction with increased ADMA.
