Brief Note: The Influence of the Menstrual Cycle on the Blood Flow Through Muscle During Isometric Exercise

Author Institution: Departments of Engineering and Physiology, Wright State Universit

Active Material Properties of the Myocardium: Correlation With Left Ventricular Function in Man

Author Institution: Department of Engineering and Physiology, Wright State UniversityThe effects of anisotrophy and nonhomogeneity of the ventricular myocardium as represented by a linear increase in the midwall effective modulus of elasticity were investigated in the present study, specifically as they effect the circumferential stress distribution. Various studies are presented suggesting a linear increase in the effective modulus of elasticity from endocardium to epicardium. In our study, this increase in the effective modulus was constrained by the approximation that stress per unit sarcomere length is constant. We evaluated 12 functionally normal cases and 9 functionally abnormal cases. The stress distribution for the 9 functionally abnormal cases was calculated, first with the normal and secondly with the abnormal variation in the modulus of elasticity. Assuming the myocardium has constant material properties that do not change with functional decomposition, the stress distributions in the first calculations indicated higher stresses through the inner half of the myocardium and lower stresses through the outer half of the myocardium as compared to the second. This finding suggests that the inner fibers are overloaded and the outer fibers are underloaded in left ventricular decompensation. The difference between the first and second stress distributions averaged 26% (range: 11% to 48%). A useful, clinical, and quantitative measure of stress loading of the sarcomeres in functionally normal and abnormal left ventricles is proposed

Effects of aging and type 2 diabetes on resting and post occlusive hyperemia of the forearm; the impact of rosiglitazone

BACKGROUND: Both Diabetes and ageing are associated with reduced vascular endothelial function. The exact relationship between the 2 and any improvements from the insulin sensitizer rosiglitazone have not been explored. METHODS: Thirty controls and sixteen subjects with type 2 diabetes participated in a series of experiments to examine the interrelationships between age, diabetes and endothelial cell function. In subjects with diabetes, the insulin sensitizer rosiglitazone (RSG), a drug also known to improve vascular function, was administered for 3 months to see how it altered these relationships. Resting forearm flows (RF) and blood flows after 4 min of vascular occlusion (PF) were measured as an index of endothelial cell function. RESULTS: RF, measured by venous occlusion plethysmography, was negatively correlated to both age and diabetes. Administration of RSG for 3 months was associated with an increase in the blood flow response to venous occlusion so that it was not significantly different than that of age matched controls. Total PF in control subjects, compared to subjects with diabetes, averaged 56.58 +/- 12.57 and 13.6 +/- 8.01 cc/100 cc tissue per min respectively, and were significantly different (p < 0.01). After 3 months on RSG, differences between PF in the two groups were no longer evident. CONCLUSION: These studies suggest a different mechanism causing a reduction in vascular reactivity with aging and diabetes

Blood pressure and heart rate response to isometric exercise: the effect of spinal cord injury in humans

Contains fulltext : mmubn000001_221516158.pdf (publisher's version ) (Open Access)Promotores : R. Schreuder, C. Brown en P. Hagoort190 p