We tested the hypothesis that intracarotid estrogen infusion increases cerebral blood flow (CBF) in a concentration-dependent manner and direct application of estrogen on pial arterioles yields estrogen receptor-mediated vasodilation. Rabbits of both genders were infused with estrogen via a branch of the carotid artery. Estrogen doses of 20 or 0.05 microg. ml(-1). min(-1) were used to achieve s...

We studied the natural history of brain air embolism by observing bubbles in the pial vessels of rabbits and the effect of different doses of intracarotid air on brain function and blood flow. We identified and then studied two doses of air; 25 microliters in five rabbits caused rapid bubble transit, recovery, and then deterioration in brain function and blood flow and 400 microliters in five r...

Many bubbles that enter the brain circulation pass through the arterioles and capillary beds and do not obstruct blood flow. Nevertheless, such bubbles could still disrupt brain function. An open-brain model in five anesthetized rabbits used the minimum dose of air (25 microliters) necessary to cause embolism of the exposed vessels, and these bubbles passed through the vessels without any trapp...

There is a need to develop new techniques for quantitative measurement of receptors expression on particular vasculature cells types. Here, we describe and demonstrate a novel method to measure quantitatively and simultaneously the expression of endothelin B receptor (ETB) on vascular smooth muscle cells (VSMC). We isolated cells from male rat tissues such as: brain pial, brain intraparenchymal...

INTRODUCTION The leptomeningeal collaterals are a subsidiary network of vascular channels that act as anastomotic channels in conditions where cerebral blood flow is pathologically altered. These secondary collateral pathways may be utilized when collateral flow through the circle of Willis is inadequate. SUMMARY OF REVIEW The review highlights the importance of leptomeningeal (pial) anastomo...

Chronic hypertension is associated with hypertrophy of cerebral blood vessels. Previous studies of the mechanical properties of cerebral vessels in chronic hypertension have examined large cerebral arteries. The goals of this study were first to develop a method to examine vascular mechanics of cerebral arterioles in vivo and second to determine whether the stiffness of cerebral arterioles is a...

Functional magnetic resonance imaging (fMRI) is the primary means used to measure brain function non-invasively in humans, because of the advantages it offers in terms of high spatiotemporal resolution and localization as compared to other non-invasive modalities (e.g. EEG, MEG). Since its emergence about 20 years ago, it has rapidly evolved into the mainstay of functional neuroimaging for neur...

The influence of norepinephrine on the diameter of single pial arteries and arterioles was investigated by adding the drug to the perivascular space with micropipettes. The mock spinal fluid solution in which the norepinephrine was dissolved contained 0, 11, or 22 mEq/liter of bicarbonate. These concentrations of bicarbonate were by themselves found to dilate, cause no change, and constrict the...

We investigated the effects of topically administered catecholamines and acetylcholine (ACh) on the cerebrocortical microcirculation and NAD/NADH redox state in chloralose-anesthetized cats. NADH fluorescence of the brain cortex and the volume of small intracortical vessels were measured by fluororeflectometry, and in most of the experiments the pial vessels were photographed simultaneously thr...