Flickering light dilates retinal arterioles and increases retinal blood flow, a response termed functional hyperemia. This response is diminished in diabetic patients even before the appearance of overt clinical retinopathy. The loss of functional hyperemia could deprive retinal neurons of oxygen and nutrients, possibly exacerbating the development of diabetic retinopathy. We have tested whethe...

We determined the role of endogenous hydrogen sulfide (H2S) in cerebral vasodilation/hyperemia and early BBB disruption following ischemic stroke. A cranial window was prepared over the left frontal, parietal and temporal cortex in mice. Transient focal cerebral Ischemia was induced by directly ligating the middle cerebral artery (MCA) for two hours. Regional vascular response and cerebral bloo...

BACKGROUND It is believed that endothelial dysfunction may be a link between systemic and ocular dysregulation in glaucoma. The aim of this study was to evaluate peripheral vascular reactive hyperemia in response to occlusion test and to correlate peripheral vascular findings with retrobulbar hemodynamics parameters in patients with normal-tension glaucoma. MATERIAL AND METHODS Forty-eight pa...

To characterize and interpret arterial spin labeling (ASL) reactive hyperemia of calf muscles for a better understanding of the microcirculation in peripheral arterial disease (PAD), we present a physiological model incorporating oxygen transport, tissue metabolism, and vascular regulation mechanisms. The model demonstrated distinct effects between arterial stenoses and microvascular dysfunctio...

Correlative studies of cortical blood flow measured by the Kr washout technique and observations of the cortical blood vessels of 10 squirrel monkeys subjected to temporary occlusion of the middle cerebral artery are described. During occlusion, cortical blood flow in core areas of ischemia decreased to 0.12 to 0.90 ml/g/min (20 to 50% of preocclusion values) and became pressure dependent with ...

To the Editor: We read with great interest Dr Huang’s study, published in Arteriosclerosis, Thrombosis, and Vascular Biology.1 We are in total agreement with the authors about the clinical relevance in the perioperative setting of the hyperemic flow velocity, measured by brachial artery Doppler ultrasound. Dr Huang suggests that reactive hyperemia increases the accuracy of the noninvasive vascu...

Arterial flow and oxygen extraction were continuously measured from an in situ, denervated loop of cat ileum. Following release of arterial occlusion of varying time periods, oxygen extraction decreased transiently, returning to control levels as the hyperemia subsided. These results suggest that the hyperemia overcompensates in attempting to repay the oxygen deficit and, consequently, oxygen e...

In pentobrabital-anesthetized open chest dogs, myocardial adenosine content is elevated by 5 or 15 seconds of left coronary artery occlusion and falls exponentially to control levels during reactive hyperemia. The rate constants for adenosine dissipation are (mean +/- SEM): -0.08 +/- 0.01 and -0.034 +/- 0.007 sec-1 after 5- and 15-second occlusion, respectively. Kinetic analysis of the reactive...

We validated a noninvasive radionuclide plethysmography technique to evaluate peripheral arterial blood flow during reactive hyperemia. This method, based on the measurement of blood volume variations during repetitive venous occlusions, was compared with strain-gauge venous impedance plethysmography. The technique uses 99mTc-labeled autologous red blood cells scintigraphy to determine the rate...

Skeletal muscle arterioles from obese Zucker rats (OZR) exhibit oxidant stress-based alterations in reactivity, enhanced alpha-adrenergic constriction, and reduced distensibility vs. microvessels of lean Zucker rats (LZR). The present study determined the impact of these alterations for perfusion and performance of in situ skeletal muscle during periods of elevated metabolic demand. During bout...