We investigated whether low-dose medroxyprogesterone acetate (MPA) combined with oral estrogen had adverse effects on endothelial function compared with oral estrogen alone in postmenopausal women ...with mild hypercholesterolemia.
Subjects were divided into two groups. One group received conjugated equine estrogen (CEE, 0.625 mg daily) orally for the first 3 months, followed by estrogen combined with MPA (2.5 mg daily) orally for an additional 3 months ( = 26). The other group received no treatment (control group, = 12). Forearm blood flow (FBF) during reactive hyperemia and after sublingual nitroglycerin administration was measured by strain-gauge plethysmography. Nitrite/nitrate, angiotensin-converting enzyme, and lipid concentrations were measured in the serum.
Both CEE and CEE combined with MPA significantly increased the FBF during reactive hyperemia. This increase was similar in both active treatment phases. No changes were seen in controls. FBF after sublingual nitroglycerin did not change over 6 months in either group. Significant and similar increases in serum concentration of nitrite/nitrate and plasma renin activity as well as decreases in angiotensin-converting enzyme activity were found in both treatment phases. No such changes occurred in the control group. There was no significant increase in high-density lipoprotein cholesterol or decrease in low-density lipoprotein cholesterol between the treatment phases. Likewise, no such changes were observed in the control group.
Our 6-month study suggests that the addition of low-dose MPA with CEE had no adverse effects on forearm resistance artery endothelial function compared with CEE alone.
We investigated the effect of NaCl on the circadian blood pressure rhythm in patients with essential hypertension classified according to the presence or absence of salt sensitivity. We obtained ...24-hour noninvasive ambulatory blood pressure measurements in 64 Japanese patients with mild to moderate essential hypertension who ate a low NaCl diet (50 mmol/d) for 1 week, followed by a high NaCl diet (340 mmol/d) for 1 week. Twenty-six patients whose mean blood pressure was increased more than 10% by NaCl loading were classified as salt sensitive. The remaining 38 patients were classified as salt resistant. The nocturnal decline in mean blood pressure was significantly smaller in salt-sensitive patients (8.3+/-1.0%) than in salt-resistant patients (11.5+/-0.9%) (P.05) during a high NaCl diet but was similar in both groups during a low NaCl diet. There was no significant difference in the prevalence of the non-dipper pattern between groups on a low NaCl diet, but the prevalence of the non-dipper pattern was significantly higher in salt-sensitive patients than in salt-resistant patients on a high NaCl diet (0.57 versus 0.26, chi2=6.4; P=.02; odds ratio, 3.82). These findings suggest that the NaCl loading blunted the nocturnal decline in blood pressure in salt-sensitive patients but not in salt-resistant patients.
This paper proposes a method for qualitatively estimating the mechanical properties of arterial walls on a beat-to-beat basis through noninvasive measurement of continuous arterial pressure and ...arterial diameter using an ultrasonic device. First, in order to describe the nonlinear relationships linking arterial pressure waveforms and arterial diameter waveforms as well as the viscoelastic characteristics of arteries, we developed a second-order nonlinear model (called the log-linearized arterial viscoelastic model) to allow estimation of arterial wall viscoelasticity. Next, to verify the validity of the proposed method, the viscoelastic indices of the carotid artery were estimated. The results showed that the proposed model can be used to accurately approximate the mechanical properties of arterial walls. It was therefore deemed suitable for qualitative evaluation of arterial viscoelastic properties based on noninvasive measurement of arterial pressure and arterial diameter.
The regulation of the intracellular concentration of Mg
2+ (Mg
2+i) is not fully understood. The level of Mg in lymphocytes is a good predictor of total body Mg status. We measured Mg
2+i and total ...Mg in rat lymphocytes by using, respectively, the fluorescent Mg
2+ indicator mag-fura-2 and atomic absorption spectrophotometry. The basal Mg
2+i in rat lymphocytes was 328±23 μmol/l. An elevation to 5 mmol/l or the removal of extracellular Mg
2+ did not affect Mg
2+i. A reduction in extracellular Na
+ did not influence Mg
2+i for 60 min. The total Mg concentration in lymphocytes also remained stable. Results suggest that the permeability of the plasma membrane to Mg
2+ is very low, and that Na
+/Mg
2+ exchange is not involved in the regulation of Mg
2+i in rat lymphocytes.
The purpose of this study was to determine the effects of aerobic exercise on endothelium-dependent vasodilation in humans. We evaluated the forearm blood flow (FBF) response to acetylcoline (ACh), ...an endothelium-dependent vasodilator, and isosorbide dinitrate (ISDN), an endothelium-independent vasodilator, before and after exercise (bicycle ergometers, 30 min, 5 to 7 times per week, for 12 weeks, 50%Vo2max) in healty young men (n=8, mean age: 27 ± 3 yr). FBF was measured using a mercury-filled Silastic strain-gauge plethysmograpy. Twelve weeks of exercise significantly augmentated ACh-induced vasodilation (7.5 ± 2.4 to 11.4 ± 5.8 ml/min/100 ml tissue, p<0.05). Aerobic exercise didn't alter ISDN-induced vasodilation. Administration of NG-monomethyl-L-arginin (L-NMMA), a nitric oxide synthase inhibitor, abolished exercise-induced augmentation of the FBF response to ACh. These findings suggest that aerobic exercise augments endothelium-dependent vasodilation in humans through the increased nitric oxide production.
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