BACKGROUND AND PURPOSE The underlying mechanisms for reductions in cerebral blood flow (CBF) during orthostasis are not completely understood. This study tested the hypothesis that sympathetic activation causes cerebral vasoconstriction leading to reductions in CBF during lower body negative pressure (LBNP). METHODS CBF velocity, arterial pressure, and end-tidal CO(2) were measured during LBN...

A mean decrease of 60% in liver blood volume was recorded by a plethysmographic technique during electrical stimulation of the hepatic nerves in anesthetized, vagotomized dogs. A decrease in pressure in the vascularly isolated carotid sinus to 40 mm Hg, from a mean control of 144 mm Hg, decreased liver blood volume by a mean of 16%; arterial blood pressure increased by a mean of 77 mm Hg. Carot...

We compared the mean arterial pressure and heart rate activity of conscious, unrestrained rats during 1-hour and 24-hour continuous recording sessions, 3 to 4 weeks after either sinoartic denervation, placement of electrolytic lesions in the nucleus tractus solitarii, or sham operations. Sinoaortic denervation and nucleus tractus solitarii lesions both eliminated the reflex bradycardia to a phe...

Although the primary emphasis of research on spontaneously hypertensive rats (SHR) tends to be on adult animals, the young SHR can have a mean arterial pressure that is elevated above normal almost proportionately as much as in adult SHR. This study attempted to determine whether the cerebral vasculature of 4- to 5-week-old SHR used existing normal mechanisms to tolerate hypertension or had mic...

Xylazine, midazolam and a midazolam/ketamine combination were administered to 6 goats in a randomised 3-way block design. All goats received all treatments with at least a 7-day interval between treatments. Statistically significant (P < 0.05) changes were observed in some of the measured cardiopulmonary variables for xylazine and midazolam/ ketamine. Xylazine administration resulted in statist...

Mean and pulsatile components of hemodynamic load are related to cardiovascular disease. Vascular growth factors play a fundamental role in vascular remodeling. The links between growth factors and hemodynamic load components are not well described. In 3496 participants from the Framingham Heart Study third generation cohort (mean age: 40 9 years; 52% women), we related 4 tonometry-derived meas...

Mean and pulsatile components of hemodynamic load are related to cardiovascular disease. Vascular growth factors play a fundamental role in vascular remodeling. The links between growth factors and hemodynamic load components are not well described. In 3496 participants from the Framingham Heart Study third generation cohort (mean age: 40±9 years; 52% women), we related 4 tonometry-derived meas...