The mechanism of the well-documented increase in aortic pulse pressure (PP) with age is disputed. Investigators assuming a classical windkessel model believe that increases in PP arise from decreases in total arterial compliance (C(tot)) and increases in total peripheral resistance (R(tot)) with age. Investigators assuming a more sophisticated pulse transmission model believe PP rises because i...

Hypervolemic anemia and normovolemic anemia were produced in dogs. Cardiac outputs increased comparably with similar degrees of anemia in the hypervolemic and normovolemic animals. No significant association between light atrial mean pressure and cardiac output was found. Right atrial and pulmonary arterial pressures increased in a degree comparable to blood volume increase. Systemic mean press...

This work was undertaken to study the mechanical factors affecting the function of the isolated heart of Helix pomatia in order to help understand the variations in heart activity observed in intact animals. Biedermann (1884), working upon the isolated heart of Helix, observed that the frequency of beat increased with distension of the heart. Biering (1929) found that in the isolated Helix hear...

Exercise stimulates increases in heart rate (HR), stroke volume (SV) and cardiac output (CO). These adaptive mechanisms are strongly dependent on the type of exercise. Both rowing and cycling are widely used for physical training worldwide; however, evidence regarding the differences in major hemodynamic parameters during rowing and cycling remains insufficient. Ten healthy male volunteers were...

We examined potential age and gender differences in cardiovascular reactivity during acute psychosocial stress in 133 normotensive participants using a cross-sectional design. Results revealed that age predicted increased systolic blood pressure (SBP) reactivity during stress (p < .001). The greater SBP reactivity found in older individuals appeared due to an age-associated increase in both car...

The cryptographic hash function provides the services of information security, authentication, integrity, non-reputation in a branch of information secret. A cryptographic hash function has been developed since MD4 was proposed by Rivest. In present, U.S standard of a hash function is SHA-1 with 160 bits of output length. It is difficult to be sure of a security of a hash function with 160 bits...

The effects of ouabain (G-strophanthin), 20 /xg/kg, were compared in 12 conscious dogs with Doppler flow transducers on the ascending aorta and left circumflex coronary artery and pressure gauges in the aorta, and in 9 of these dogs after general anesthesia with Na pentobarbital. In conscious dogs ouabain caused an initial bradycardia, but heart rate returned almost to control at 15 to 30 minut...

We systematically modified isoproterenol's chemical structure to reduce chronotropic, arrhythmogenic, and vascular side effects. Experiments on dogs showed that the resulting drug, dobutamine, had an inotropic efficacy as great as that of epinephrine due to a direct action on beta1 cardiac receptors. However, unlike epinephrine, dobutamine's effect on alpha and beta2 vascular receptors was slig...

Systemic and coronary hemodynamics were assessed before and during a reduction in carotid transmural pressure. This reduction was induced by means of a pneumatic neck chamber in 15 normal subjects and 15 hypertensive patients with a normal coronary arteriogram. A reduced baroreflex responsiveness was demonstrated in hypertensive patients as compared with normal subjects by evaluating both the r...