UNLABELLED The brain is critically dependent on the regulation of blood flow to nourish active neurons. One widely held hypothesis of blood flow regulation holds that active neurons stimulate Ca(2+) increases in glial cells, triggering glial release of vasodilating agents. This hypothesis has been challenged, as arteriole dilation can occur in the absence of glial Ca(2+) signaling. We address t...

We previously found that local O2 extraction efficacy in isolated pump-perfused intestine was enhanced when systemic reflex vasoconstriction was stimulated by hypovolemia (Samsel, R.W., and P.T. Schumacker. 1994. J. Appl. Physiol. 77: 2291-2298). The microvascular mechanism underlying this beneficial effect could involve a redistribution of flow between mucosa and serosa, or an adjustment in th...

Adenosine is a widely used pharmacological agent to induce a "high-flow" control condition to study the mechanisms of exercise hyperemia, but it is not known how well an adenosine infusion depicts exercise-induced hyperemia, especially in terms of blood flow distribution at the capillary level in human muscle. Additionally, it remains to be determined what proportion of the adenosine-induced fl...

This paper is concerned with a mathematical and numerical study of liquid dynamics in a horizontal capillary. We derive a two-liquids model for the prediction of capillary dynamics. This model takes into account the effects of real phenomena: like the outside flow action, or the entrapped gas inside a closed-end capillary. Moreover, the limitations of the one-dimensional model are clearly indic...

Pulmonary capillary blood flow was measured in man during slow breathing by a modification of the body plethysmogTaph technique for measuring N2O uptake. In seated subjects breathing slowly, flow was significantly higher during inhalation. In supine subjects whose legs were raised, the difference between inhalation and exhalation was not significant. Flow was usually greater during tidal inhala...

After cardiac ischaemia, a prolonged decrease of coronary microvascular perfusion often occurs even after flow is restored in an upstream artery. This 'no-reflow' phenomenon worsens patient prognosis. In the brain, after stroke, a similar post-ischaemic 'no-reflow' has been attributed to capillary constriction by contractile pericytes. We now show that occlusion of a rat coronary artery, follow...

[1] This work presents a series of numerical modeling studies that investigate the hydrogeologic conditions required to form capillary barriers and the effect that capillary barriers have on fluid flow and tracer transport processes in the unsaturated fractured rock of Yucca Mountain, Nevada, a potential site for storing high-level radioactive waste. The modeling approach is based on a dual-con...

Capillary-driven micro flow allows liquid transport by interfacial force without external pressure or momentum. Theoretical and experimental studies have been conducted to predict the movement of the flow meniscus in the application of capillary underfill flows. In a flip chip package, two-dimensional motions of flow front through solder bumps can result in unwanted air void formation because t...

Further evidence has been obtained that L-norepinephrine infusions markedly decreases cutaneous capillary blood flow in the nailfold. Sustained ischemia of the capillary bed occurred prior to the attainment of hypertensive diastolic arterial blood pressure levels. Corroborative evidence of this nailfold capillary ischemia was obtained from the capillary reactive hyperemia that followed the abru...

PURPOSE To study the flow velocity of erythrocytes and leukocytes in the same retinal capillaries in cat eyes. METHODS Blood cells from cats were stained with fluorescent label and reinjected into the animals. An electro-optical device combined with a highly sensitive CCD camera detected the fluorescent signal from the labeled blood cells. The signal was stored on a videotape (VHS-PAL, 25 fra...