The distensibility of the arterial wall progressively decreases with age, and the aging of the arterial wall may be responsible for the decrease of central arterial compliance and the consequent rise of systolic blood pressure (SBP) in the elderly. We hypothesized that an increase in daily physical activity (DPA) might have a favorable effect on systemic arterial compliance (SAC : an index of central arterial compliance) and lower SBP in the elderly. We therefore investigated relationships among DPA, SAC and SBP cross-sectionally in 92 middle-aged and elderly individuals (30 males, 62 fe- males ; aged 64 ± 8 years, mean ± SD). DPA was estimated by using an accelerometer as expended calories. SAC was calculated from the finger pulse pressure waveform recorded by using a Portapres and the stroke volume obtained from the same pressure waveform based on the volume-clamp method. Preliminarily in 37 subjects (17 male, 20 females ; aged 25-97 years), we confirmed a significant negative correlation between the simultaneously measured SAC and aortic pulse wave velocity (r=-0.68, p<0.0001). Correlation analysis and path analysis applied to the hypothetical model demonstrated that SBP was directly affected by both DPA and the SAC which decreased with age, and that DPA had an increasing effect on SAC, i. e. DPA might have a suppressive effect on the rise of SBP not only directly but also indirectly through SAC. These results suggest that an increased level of daily physical activity could improve the age-dependent decrease of central arterial compliance and the rise of systolic blood pressure in middle-aged and elderly humans.
Cardiovascular complications are an important feature of diabetes mellitus (DM). Abnormal and decreased coronary collateral development has been implicated in the pathogenesis of cardiac complications in DM. More recently, decreased expression of vascular endothelial growth factor (VEGF) and its receptors has been found in diabetic heart. To our knowledge, no study has focused on the therapeutic improvement associated with VEGF in diabetic heart. DM was induced by intraperitoneal injection of streptozotocin (65 mg/kg) in Sprague-Dawley rats, while control rats received only citrate buffer. After 1 week, the streptozotocin-treated rats were randomly divided into two groups: one group received the selective endothelin (ET) type A receptor antagonist TA-0201 at a dose of 1 mg/kg/day for 2 weeks by osmotic mini-pump, and the vehicle group received saline only. The plasma glucose level was 504 +/- 75 mg/dl in the diabetic rats and was unchanged by treatment with ET antagonist. The body weight was decreased in the diabetic rats compared with the control rats, but the left ventricular (LV)-body weight ratio was increased in the diabetic group and was unaffected by treatment with ET antagonist. mRNA expression of VEGF and its receptors (Flt-1 and Flk-1) in the LV tissues was assessed using real-time polymerase chain reaction. VEGF expression was significantly decreased in diabetic heart and was greatly improved by treatment with ET antagonist. The expression of VEGF receptors was down-regulated in early diabetic heart but was not recovered by treatment with ET antagonist. ET and its receptor A might have differential regulation on the gene expressions of VEGF and its receptors in early diabetic heart.
